Gnss receiver positioning system

ABSTRACT

A method of extracting pseudorange information using a cellular device. A Global Navigation Satellite System (GNSS) chipset which is physically remote from a cellular device is accessed which provides raw GNSS observables information based upon signals received from a circularly polarized GNSS antenna. The raw GNSS observables information is wirelessly transmitted from the GNSS chipset to the cellular device. The raw GNSS observables information is extracted by a processor of the cellular device. The raw GNSS observables information, in addition to GNSS corrections from at least one correction source, is used by the processor to determine a position of the circularly polarized GNSS antenna.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority and is a continuation-in-partapplication of co-pending U.S. patent application Ser. No. 14/035,884,filed on Sep. 24, 2013 entitled, “EXTRACTING PSEUDORANGE INFORMATIONUSING A CELLULAR DEVICE” by Rudow et al., having Attorney Docket No.TRMB-3172.CIP1, and assigned to the assignee of the present applicationand to the extent not repeated herein; the contents of U.S. patentapplication Ser. No. 14/035,884 are hereby incorporated herein byreference.

This application claims priority to and benefit of co-pending U.S.Provisional Patent Application No. 61/746,916, filed on Dec. 28, 2012entitled, “IMPROVED GPS/GNSS ACCURACY FOR A CELL PHONE” by Rudow et al.,having Attorney Docket No. TRMB-3172.PRO, and assigned to the assigneeof the present application; the contents of U.S. Provisional PatentApplication No. 61/746,916 are hereby incorporated herein by reference.

Application Ser. No. 14/035,884, claims priority to and is acontinuation-in-part to the co-pending patent application Ser. No.13/842,447, Attorney Docket Number TRMB-3172, entitled “OBTAININGPSEUDORANGE INFORMATION USING A CELLULAR DEVICE,” by Richard Rudow, withfiling date Mar. 15, 2013, and assigned to the assignee of the presentapplication, the disclosure of which was incorporated by reference intoapplication Ser. No. 14/035,884.

BACKGROUND

The Global Positioning System (GPS) and its extensions in the GlobalNavigation Satellite Systems (GNSS) have become thoroughly pervasive inall parts of human society, worldwide. GPS and GNSS receivers in theform of chipsets have become widely incorporated into cell phones andother types of cellular devices with cellular-based communicationsequipment.

Typically, cellular devices include highly integrated GNSS chipsets thatare designed to work with the E-911 service primarily, and are notdesigned to provide anywhere near a full range of features and outputs.They do provide a position fix, but are not designed to make availablevery many other parameters of interest. All GNSS receivers must acquire,track and decode a data message that conveys information about thelocation of the satellites in space, and time information. The principaladditional parameter obtained is the “pseudorange.” However,conventionally, this set of data is not available as an output from thecell phone GNSS chipsets for use by the cellular device itself.Conventionally, in circumstances where it is available, it is underaccess control by the vendor. Furthermore, when handheld electronicdevices implementing GNSS capabilities are used, they can exhibitreduced performance due to obscuration of a GNSS satellite signals. Thiscan be the result of trees, or structures which obscure the signals, ordue to the position and/or orientation of the device when in use.Furthermore, due to size limitations of handheld devices, the antennadesign used may not be optimal for receiving GNSS signals.

BRIEF DESCRIPTION OF THE DRAWING

The accompanying drawings, which are incorporated in and form a part ofthis application, illustrate embodiments of the subject matter, andtogether with the description of embodiments, serve to explain theprinciples of the embodiments of the subject matter. Unless noted, thedrawings referred to in this brief description of drawings should beunderstood as not being drawn to scale. Herein, like items are labeledwith like item numbers.

FIG. 1A depicts a block diagram of a cellular device for extractingpseudorange information, according to one embodiment.

FIG. 1B depicts a block diagram of a cellular device for extracting andprocessing pseudorange information, according to one embodiment.

FIG. 1C depicts decision logic for determining whether to apply WAAS(Wide Area Augmentation System) corrections or DGPS (Differential GlobalPositioning System) corrections, according to one embodiment.

FIG. 1D depicts a block diagram of a cellular device for extractingpseudorange information, according to one embodiment.

FIG. 2 depicts a block diagram of multiple sources for providingpositioning correction information to a cellular device for processingpseudorange information, according to one embodiment.

FIG. 3 depicts a conceptual view of pseudorange measurements, accordingto various embodiments.

FIG. 4 depicts a flowchart for determining an RTK (Real Time Kinematic)position solution, according to one embodiment.

FIG. 5A is a flowchart of a method for performing a carrier phasesmoothing operation using real carrier phase information, according toone embodiment.

FIG. 5B is a flowchart of a method for generating reconstructed carrierphase information based on Doppler shift, according to one embodiment.

FIG. 6 depicts a flowchart of a method of extracting pseudorangeinformation using a cellular device, according to one embodiment.

FIGS. 7A-10 depict flowcharts of methods of improving the positionaccuracy using one or more position accuracy improvements, according tovarious embodiments.

FIG. 11 depicts a flowchart a method of accessing and processingextracted pseudorange information, according to one embodiment.

FIG. 12 depicts a block diagram of a GNSS receiver, according to oneembodiment.

FIG. 13 depicts an example Kalman filtering process, according tovarious embodiments.

FIG. 14 is a block diagram of components of a GNSS receiver positioningsystem in accordance with various embodiments.

FIGS. 15A-15M example uses of a GNSS receiving component in accordancewith various embodiments.

FIGS. 16A-16D are block diagrams of components of a GNSS receivingcomponent in accordance with at least one embodiment.

FIG. 17 is a block diagram of components of a GNSS receiving componentin accordance with one embodiment.

FIG. 18 is a flowchart of a method of extracting pseudorange informationusing a cellular device in accordance with various embodiments.

DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to various embodiments of thesubject matter, examples of which are illustrated in the accompanyingdrawings. While various embodiments are discussed herein, it will beunderstood that they are not intended to limit to these embodiments. Onthe contrary, the presented embodiments are intended to coveralternatives, modifications and equivalents, which may be includedwithin the spirit and scope the various embodiments as defined by theappended claims. Furthermore, in the following Description ofEmbodiments, numerous specific details are set forth in order to providea thorough understanding of embodiments of the present subject matter.However, embodiments may be practiced without these specific details. Inother instances, well known methods, procedures, components, andcircuits have not been described in detail as not to unnecessarilyobscure aspects of the described embodiments.

Unless specifically stated otherwise as apparent from the followingdiscussions, it is appreciated that throughout the description ofembodiments, discussions utilizing terms such as “accessing,”“transmitting,” “extracting,” “using,” “smoothing,” “correcting,”“creating,” “storing,” “determining,” “disposing,” and “coupling” totransform the state of a computer system,” or the like, refer to theactions and processes of a computer system, data storage system, storagesystem controller, microcontroller, hardware processor, or similarelectronic computing device or combination of such electronic computingdevices. The computer system or similar electronic computing devicemanipulates and transforms data represented as physical (electronic)quantities within the computer system's/device's registers and memoriesinto other data similarly represented as physical quantities within thecomputer system's/device's memories or registers or other suchinformation storage, transmission, or display devices.

Overview

Cellular devices, such as cell phones and non-voice enabled cellulardevices, possesses pseudorange information that can be used in surveyingand other positioning operations. Conventionally, however, thepseudorange information from cellular device chipsets are only availableunder a limited set of conditions, usually only when performing a E-911service call, and then only for use by the Assisted GPS service locatedin conjunction with the E-911 service facility. Therefore, according toone embodiment, an embedded GNSS chipset is employed with in a cellulardevice, which: a) calculates pseudorange information for use by the GNSSchipset; and b) permits extraction of this pseudorange information bythe cellular device in which it is embedded. As will be discussed, thepseudorange information from the GNSS chipset is extracted for useelsewhere in the cellular device outside of the GNSS chipset. Finally, aGNSS positioning system with a remote antenna component will bediscussed.

Examples of Systems for Extracting Pseudorange Information

FIG. 1A depicts a block diagram of a cellular device 100 for extractingpseudorange information, according to one embodiment. Examples of acellular device 100 include a cell phone, a non-voice enabled cellulardevice, and a mobile hand-held GNSS receiver. The cellular device may bemobile or stationary. The cellular device may be hand-holdable orincorporated as a portion of a system which is not hand-holdable. Insome embodiments, a cellular device, such as cellular device 100, may beutilized as a portion of a navigation system, security system, safetysystem, telematics device/box, or the like. In some embodiments,cellular device 100 may be utilized as sub-system of the vehicle mountedportion of a vehicle safety system, security system, and/or navigationsystem. The vehicle mounted portion of the OnStar® vehicle safety,vehicle security, and vehicle navigation system that is utilized in manyvehicles is one non-limiting example of a system which may includecellular device 100.

As depicted in FIG. 1A, the cellular device 100 includes a GNSS chipset170, a GNSS receiver 107, a processor 172 that is part of the GNSSreceiver 107, a chipset accessor logic 141, a pseudorange informationextractor logic 142, an improved accuracy Secure User Platform Location(SUPL) client 101, a pseudorange information bridger logic 143, apseudorange information processing logic 150, an operating system 160, alocation manager logic 161, a location displayer logic 162, hardware 180that is outside of the GNSS receiver 107. According to one embodiment,the chipset accessor logic 141, the pseudorange information extractorlogic 142, the pseudorange information processing logic 150, and thepseudorange information bridger logic 143 are a part of the improvedaccuracy SUPL client 101.

According to one embodiment, the hardware 180 includes a hardwareprocessor 109 and memory 210. An example of a hardware processor 109 isa central processing unit. An example of hardware memory 210 is computerreadable storage, such as, but not limited to, a disk, a compact disk(CD), a digital versatile device (DVD), random access memory (RAM) orread only memory (ROM). The hardware memory 210 is physical and,therefore, tangible, according to one embodiment. The hardware memory210, according to another embodiment, is non-transitory.

According to one embodiment, the processor 172 and the GNSS receiver 107are a part of the GNSS chipset 170. According to one embodiment, thechipset accessor logic 141, pseudorange information extractor logic 142,the pseudorange information bridger logic 143, the improved accuracySUPL client 101, the operating system 160, and the processor 109 arelocated in a portion of the cellular device 100 that is outside of theGNSS chipset 170. The location manager logic 161 can be a part of theoperating system 160 and external to the GNSS chipset 170. According toone embodiment, the location displayer logic 162 is a part of thelocation manager logic 161. According to one embodiment, the chipsetaccessor logic 141, pseudorange information extractor logic 142, thepseudorange information processing logic 150, pseudorange informationbridger logic 143, and improved accuracy SUPL client 101 are applicationprogramming interfaces (API) function applications that reside in memoryof the cellular device 100 and are executed by a processor 109 of thecellular device 100.

According to one embodiment, the GNSS receiver 107 is capable ofreceiving signals from GPS satellites, GLONASS satellites, or from acombination of satellites from different constellations. The GNSSreceiver 107 can perform GPS measurements to derive raw measurement datafor a position of the cellular device 100. The raw measurement data canprovide an instant location of the cellular device 100. According to oneembodiment, the raw measurement data is the pseudorange information thatis extracted (also referred to as “extracted pseudorange information”).Examples of the extracted pseudorange information are uncorrectedpseudorange information, observed pseudorange information, or unsmoothedpseudorange information, or a combination thereof. Conventionally, theraw measurement data is only for use by the GNSS chipset 170 and theGNSS chipset 170 calculates pseudorange information that is only for useby the GNSS chipset 170. Examples of pseudorange information areuncorrected pseudorange information, smoothed pseudoranges, andcorrected pseudoranges. Examples of corrections used to improve accuracyof a position fix include differential GNSS corrections (DGPS), highprecision GNSS satellite orbital data, GNSS satellite broadcastephemeris data, and ionospheric and tropospheric error corrections anderror projections based on location.

The GNSS chipset 170 has a processor 172 and, therefore, is capable ofprocessing information, such as pseudorange information, itself.However, according to various embodiments, information that the GNSSchipset 170 has can be extracted from the GNSS chipset 170 and processedoutside of the GNSS chipset 170 instead of by the GNSS chipset 170 usingits own processor 172, in order to provide an improved accuracy positionfix.

The chipset accessor logic 141 is configured for accessing the GNSSchipset 170. The pseudorange information extractor logic 142 isconfigured for extracting the pseudorange information from the accessedGNSS chipset 170. The extracted pseudorange information can be receivedand stored continuously. The pseudorange information bridger logic 143is configured for bridging the pseudorange information from the GNSSchipset 170 to the location manager logic 161 that resides in theoperating system 160 of the cellular device 100.

According to one embodiment, the chipset accessor logic 141, thepseudorange information extractor logic 142, the pseudorange informationprocessing logic 150 and pseudorange information bridger logic 143 are apart of an improved accuracy SUPL client 101. For example, The SUPLclient 101 can interface between the GNSS chipset 170 and the locationmanager logic 161, which resides in the operating system 160.

The pseudorange information can be obtained from the processor 172 ofthe GNSS receiver 107. The GNSS chipset 170 may be designed, forexample, by the manufacturer of the GNSS chipset 170, to providerequested information, such as pseudorange information, in response toreceiving the command. The pseudorange information may be extracted fromthe GNSS chipset 170 using the command that the manufacturer hasdesigned the GNSS chipset 170 with. For example, according to oneembodiment, the GNSS chipset 170 is accessed using an operation that isa session started with a message that is an improved accuracy SecureUser Platform Location (SUPL) start message or a high precision SUPLINIT message. According to one embodiment, the message is a customcommand that is specific to the GNSS chipset 170 (also referred to as “aGNSS chipset custom command”) and by which the improved accuracy SUPLclient 101 can gain access to the raw measurements of the GNSS chipset170. Access may be controlled by the chipset manufacturer and a suitablekey made available for use in the SUPL for obtaining access to thepseudoranges. A suitable key is an example of a “custom command.”

A worker thread associated with the SUPL client 101 can monitor the rawmeasurements delivered by the GNSS chipset 170 into the GNSS chipset170's memory buffers, cache the raw measurements and use the rawmeasurements to determine a position fix. The pseudorange informationextractor logic 142 and the pseudorange information processing logic 150can be associated with the worker thread. For example, the pseudorangeinformation extractor logic 142 can cache the raw measurements and thepseudorange information processing logic 150 can determine the location.

According to one embodiment, a worker thread is a light weight processthat executes a specific sequence of tasks in the background. The taskscan be of long term and/or at times periodic in nature. The workerthread can assist in helping the main thread, which may also be referredto as the main program or main task, with specific functions. Workerthreads can be started when these functions of the sequence of tasks areto be executed. A worker thread can remain in the active state as longas its respective functions are being executed. A worker thread mayterminate itself, when it completes its functions or when it reaches apoint where it can no longer continue to function, for example, due toan irrecoverable error. A worker thread can post its status to the mainthread when it ends. Examples of posted status are completion ortermination. A worker thread may also post to the main thread the levelof progress of its functions periodically. At a given point in time,there may be many such worker threads in progress at the same time.Worker threads may maintain some sort of synchronization amongstthemselves depending upon the tasks they are intended for. The mainthread may terminate a worker thread, for example, when the functions ofthat worker thread are no longer needed or due to other executionchanges in the system.

According to one embodiment, the cellular device 100 can improve theaccuracy of the extracted pseudorange information. For example, thepseudorange information processing logic 150 can improve the accuracy ofthe extracted pseudorange information, as will become more evident.

The output of the pseudorange information processing logic 150 can beused for determining the location of the cellular device 100. Forexample, a latitude, longitude and altitude can be determined based onthe output of the pseudorange information processing logic 150, whichcan be displayed by the location displayer logic 162.

According to one embodiment, the pseudorange information bridger logic143 communicates the output from the pseudorange information processinglogic 150 to the location manager logic 161 in the operating system 160.According to one embodiment, the output of the pseudorange informationprocessing logic 150 is a location that is defined in terms of latitude,longitude, and altitude. The methods are well-known in the GPS arts. Thepseudoranges are used to first determine a location the WGS-84coordinate system of the Global Positioning System, and then convertedinto latitude, longitude, and elevation.

The location displayer logic 162 can display the location with respectto a digital representation of a map available, for example, from thirdparties via download to the cellular device.

FIG. 1B depicts a block diagram of a portion of a cellular device 100,100D for extracting pseudorange information, according to oneembodiment. The cellular device 100, 100D includes accessing-logic 110Band processing logic 150. The accessing logic 110B includes extractinglogic 112B and receiving logic 114B. The extracting logic 112B includespseudorange information extracting logic 142, satellite-basedaugmentation system (SBAS), extracting logic 112B-5, WAAS extractinglogic 112B-2, Doppler shift extracting logic 112B-3, and carrier phasemeasurement extracting logic 112B-4. According to one embodiment, WAASis an example of SBAS. According to one embodiment, SBAS extractinglogic 112B-5 includes WAAS extracting logic 112B-2.

Examples of satellite-based augmentation system (SBAS) are Indian GPSaided Geo Augmented Navigation System (GAGAN), European GeostationaryNavigation Overlay Service (EGNOS), Japanese Multi-functional SatelliteAugmentation System (MSAS), John Deere's StarFire, WAAS, and Trimble'sOmniStar.

As depicted in FIG. 1B, the pseudorange information processing logic 150includes pseudorange-correction-logic 151,pseudorange-carrier-phase-smoothing-logic 152, position accuracyimprovement determination logic 180B and determining position fix logic170B. Examples of “improving” are “smoothing” or “correcting,” or acombination thereof. The pseudorange-correction-logic 151 includes WAASlogic 151A, DGPS logic 151B, Precise Point Positioning (PPP) logic 151C,RTK logic 151D, VRS (Virtual Reference Station) logic 151E, and RTXlogic 151F. The pseudorange-carrier-phase-smoothing-logic 152 includesreal carrier phase logic 152A and reconstructed carrier phase logic152B. According to one embodiment, the accessing-logic 110B and theprocessing logic 150 reside in the improved accuracy SUPL client 101.

Examples of pseudorange information are extracted pseudoranges,corrected pseudoranges, smoothed pseudoranges, or a combination thereof,among other things. Examples of pseudorange corrections include WideArea Augmentation System (WAAS) corrections, Differential GlobalPositioning System (DGPS) corrections, Precise Point Positioning (PPP)corrections, Real Time Kinematic (RTK) corrections, and VirtualReference Station (VRS) corrections. Examples of carrier phaseinformation include real carrier phase and reconstructed carrier phaseinformation.

The extracting logic 112B can extract various types of information fromthe GNSS chipset 170, as discussed herein. For example, the extractinglogic 112B includes pseudorange information extracting logic 142, WAASextracting logic 112B-2, Doppler extracting logic 112B-3, and carrierphase measurement extracting logic 112B-4. According to one embodiment,the extracting logic 112B can be used to extract these various types ofinformation from the GNSS chipset 170 in a similar manner that thepseudorange information extractor logic 142 extracts pseudorangeinformation from the GNSS chipset 170, for example, using an SUPL Client101 that employs a command designed or provided by the manufacturer ofthe GNSS chipset 170, as described herein. More specifically, the WAASextracting logic 112B-2, the Doppler extracting logic 112B-3, andcarrier phase measurement extracting logic 112B-4 can employ commandsdesigned or provided by the manufacturer of the GNSS chipset 170 toextract respectively WAAS, Doppler information, and carrier phasemeasurements for real carrier phase information.

The receiving logic 114B receives other types of information that arenot extracted from the GNSS chipset 170. The receiving logic 114B canreceive the information in response to a request (also commonly known as“pulling”) or receive the information without the information beingrequested (also commonly known as “pushing”). “Obtaining” and“accessing” can be used interchangeably, according to variousembodiments.

Table 1 depicts the types of information that are extracted from theGNSS chipset or received without extraction, as discussed herein,according to various embodiments.

TABLE 1 Types of Information that are Extracted from the GNSS Chipset orReceived without Extraction Extracted Received Pseudorange InformationWAAS/SBAS Doppler Shift Information DGPS Carrier Phase Measurements forreal carrier RTK phase information WAAS/SBAS Not Applicable

The information depicted in the extracted column can be extracted fromthe GNSS chipset 170 using the SUPL client 101 in a manner similar toextracting pseudorange information, as discussed herein. WAAS may beextracted or received, for example, over the Internet. When this Dopplershift information is available but real carrier phase information isnot, the extracted Doppler shift information can be integrated byprocessor 109, for example, to reconstruct carrier phase information.Techniques for reconstructing carrier phase information from Dopplershift information are well known in the art. Any one or more of theinformation depicted in Table 1 can be processed by the cellular device100, for example, using the processor 109 that is outside of the GNSSchipset 170.

The pseudorange-carrier-phase-smoothing-logic 152 can smooth pseudorangeinformation by applying carrier phase information to the pseudorangeinformation.

The pseudorange-carrier-phase-smoothing-logic 152 receives rawpseudorange information from the accessing logic 110B. The carrier phaseinformation may be reconstructed carrier phase information or realcarrier phase information.

The pseudorange-correction-logic 151 can correct pseudorangeinformation. For example, the pseudorange-correction-logic 151 canreceive pseudorange information and apply pseudorange corrections to thepseudorange information. Examples of the pseudorange informationreceived by the pseudorange-correction-logic 151 include extractedpseudorange information, DGPS corrected pseudoranges, and smoothedpseudoranges that were smoothed, for example, using either real carrierphase information or reconstructed carrier phase information. Examplesof pseudorange corrections that can be applied to the receivedpseudorange information are WAAS corrections, DGPS corrections, PPPcorrections, RTK corrections and VRS corrections. The PPP logic 151Cperforms Precise Point Positioning (PPP) processing on pseudorangeinformation. According to one embodiment, RTX™ is proprietary form ofPPP developed by Trimble Navigation Limited. It should be appreciatedthat there are other forms of Precise Point Positioning which mayoperate using similar principles.

The pseudorange information processing logic 150 may also include adetermining position fix logic 170B that performs, for example, a leastsquares solution 171B can be performed after the extracted pseudorangeinformation is improved by the pseudorange-correction-logic 151 or thepseudorange-carrier-phase-smoothing-logic 152, or a combination thereofand prior to transmitting the output to the pseudorange informationbridger logic 143. According to one embodiment, the determining positionfix logic 170B resides in the processing logic 150. Least-squaressolution methods are well-known in the position determination arts.

According to one embodiment, extracted pseudorange information is passedfrom the pseudorange information extractor logic 142 to the smoothinglogic 152 where it is smoothed at either real carrier phase logic 152Aor reconstructed carrier phase logic 152B. According to one embodiment,the smoothed pseudorange information is communicated from the smoothinglogic 152 to the correcting logic 151 for further correction, where oneor more corrections may be performed. If a plurality of corrections isperformed, they can be performed in various combinations. If carrierphase smoothing is not possible, the extracted pseudorange informationcan be communicated from pseudorange information extractor logic 142 tocorrection logic 151. One or more of the logics 152A, 152B, 151A, 151E,151F in the processing logic 150 can communicate with any one or more ofthe logics 152A, 152B, 151A, 151E 151F in various orders andcombinations. Various embodiments are not limited to just thecombinations and orders that are described herein. According to oneembodiment, extracted pseudorange information may not be smoothed orcorrected. In this case, unsmoothed uncorrected pseudorange informationcan be communicated from logic 142 to logic 170B.

The cellular device 100 may also include aposition-accuracy-improvement-determination-logic 180B for determiningwhether to apply any improvements and if so, the one or more positionaccuracy improvements to apply to the extracted pseudorange information.For example, the cellular device 100 may be preconfigured based on thesignals that are available to the cellular device 100 or a user of thecellular device 100 may manually configure the cellular device 100. Forexample, the cellular device 100 can display the signals that areavailable to the user and the user can select which signals they desirefrom the displayed list of signals. The configuration information,whether preconfigured or manually configured by the user, can be storedfor example, in a look up table in the cellular device 100. Examples ofposition improvements that can be determined by the position accuracyimprovement determination logic 180B are real carrier phase information,reconstructed carrier phase information, WAAS, DGPS, PPP, RTX™, RTK andVRS. The position accuracy improvement determination logic 180B can beused to determine to reconstruct carrier phase information based onDoppler shift if real carrier phase information is not available, forexample. The position-accuracy-improvement-determination-logic 180B,according to one embodiment, is a part of the SUPL client 101.

Extracted pseudorange information without any additional improvementsprovides 4-5 meters of accuracy. Various combinations of positionaccuracy improvements can be applied to extracted pseudorangeinformation (EPI) according to various embodiments, where examples ofposition accuracy improvements include, but are not limited to, WideArea Augmentation System (WAAS) pseudorange corrections, DifferentialGPS (DGPS) pseudorange corrections, Precise Point Positioning (PPP)processing, RTX™, Real Time Kinematic (RTK), Virtual Reference Station(VRS) corrections, real carrier phase information (real CPI) smoothing,and reconstructed carrier phase information (reconstructed CPI)smoothing.

One or more of the logics 110B, 112B, 114B, 142, 112B-2, 112B-3, 180B,152, 152A, 152B, 151, 151Aj-151F, 170B, 171B can be executed, forexample, by the processor 109 of the cellular device 100 that is locatedoutside of the GNSS chipset 170.

Table 2 depicts combinations of information that result in a positionfix 172B, according to various embodiments. However, various embodimentsare not limited to the combinations depicted in Table 2.

TABLE 2 Combinations of Information that Result in a Position FixCombination Identifier Combinations of Information that Result in aPosition Fix 1 Extracted pseudorange information (EPI) 2 EPI + Real orReconstructed Carrier Phase Information (CPI) 3 EPI + CPI + WAAS 4 EPI +CPI + WAAS + DGPS 5 EPI + CPI + DGPS 6 EPI + CPI + DGPS + PPP 7 EPI +DGPS 8 EPI + DGPS + WAAS 9 EPI + DGPS + PPP 10 EPI + RTK 11 EPI + VRS

FIG. 1C depicts decision logic 151H for determining whether to applySBAS corrections 151G, WAAS corrections 151A, PPP corrections 151C, RTX™corrections 151F or DGPS corrections 151B, according to one embodiment.According to one embodiment, the SBAS corrections that are applied areWAAS corrections. According to one embodiment, the decision logic 151His located in the position accuracy improvement determination logic 180Bor the correction logic 151.

According to one embodiment, a first position is determined by anavailable means. For example, the first position may be based onuncorrected unsmoothed extracted pseudorange information, cellular towertriangulation, Wi-Fi (Wireless-Fidelity) triangulation or other means. Alevel of precision may be selected, for example, by a user orpreconfigured into the cellular device, where DGPS or one or more ofSBAS, WAAS, RTX™, PPP would be used to achieve that level of precision.The decision logic 151H can access the level of precision and receivetwo or more reference station locations by sending a message to adatabase enquiring about nearby reference stations for DGPS. Thedecision logic 151H can determine the distance between the cellulardevice 100 and the nearest reference station. If the distance is greaterthan some selected distance threshold, the decision logic 151H can usePPP, RTX™, SBAS or WAAS, instead of DGPS. If the distance is less thanthe selected distance threshold, the decision logic 151H can use DGPSinstead of PPP, RTX™, SBAS or WAAS. According to one embodiment, a rangefor a distance threshold is approximately 20 to 60 miles. According toone embodiment, the distance threshold is approximately 60 miles.

If the decision logic 151H determines to apply DGPS corrections at DGPSlogic 151B resulting in DGPS corrected smoothed pseudoranges, furthercorrections can be made using the orbit-clock information contained inthe PPP corrections. For example, a position fix can be determined basedon the DGPS corrected smoothed pseudoranges and the PPP corrections. Theposition fix can be determined external to the GNSS chipset, forexample, at the processing logic 150.

The cellular device 100 may be configured with the distance threshold,for example, by the manufacturer of the cellular device 100 or by a userof the cellular device 100. The cellular device 100 may be configuredwith the distance threshold through service that is remote with respectto the cellular device 100 or may be configured locally. The distancethreshold can be selected based on a degree of position accuracy that isdesired.

FIG. 1D depicts a block diagram of a cellular device 100D for extractingpseudorange information, according to one embodiment.

As depicted in FIG. 1D, the GNSS chipset 170 is located on a system on achip (SOC) substrate (SOCS) 190.

As described herein, various information can be extracted from the GNSSreceiver 1130, such as pseudorange information, Doppler ShiftInformation, Real Carrier Phase Measurement, WAAS and SBAS. Other typesof processing information output by the GNSS receiver 1130 can beignored.

A Cell device 100D's hardware architecture includes discreet physicallayout and interconnection of multiple chipsets for processing and forspecial purposes such as a GNSS chipset 170. In addition, newerarchitectures involve further integration of chipsets in the “system ona chip” (SoC) configuration. In this configuration, the GNSS chipset 170can still be a complete element capable of delivering a PVT (positionvelocity and time) solution. However in an embodiment, the pseudorangeinformation, carrier phase, and/or Doppler measurements, along with WAAScorrections if available, are extracted prior to further signalprocessing in the GNSS chipset 170 and are processed using differentalgorithms and corrections data for developing an improved accuracy PVTsolution. In so doing the deleterious effects of multipath and othererror sources may be minimized. Further the GNSS chipset 170 outputs areignored and not displayed when the external processing is employed andthe higher-accuracy PVT data is available.

FIG. 2 depicts a block diagram of a set of correction delivery optionsfor providing positioning information to a cellular device forextracting pseudorange information, according to one embodiment.Examples of a cellular device 200 include a cell phone, a non-voiceenabled cellular device, and a mobile hand-held GNSS receiver. Thecellular device may be mobile or stationary.

The cellular device 200 includes a bus 216, a satellite receiver 206, aGNSS receiver 107, an FM radio receiver 208, a processor 109, memory210, a cellular transceiver 211, a display 212, audio 213, Wi-Fitransceiver 214, IMU 215, image capturing device 240, and operatingsystem 160. Components 206, 107, 208, 109, 210, 211, 212, 213, 214, 215,and 240 are all connected with the buss 216.

In FIG. 2, a plurality of broadcast sources is used to convey data andmedia to a cellular device 200. As an example, cellular device 200 canreceive broadcast signals from communication satellites 201 (e.g.,two-way radio, satellite-based cellular such as the Inmarsat or Iridiumcommunication networks, etc.), global navigation satellites 202 whichprovide radio navigation signals (e.g., the GPS, GNSS, GLONASS, GALILEO,BeiDou, Compass, etc.), and terrestrial radio broadcast (e.g., FM radio,AM radio, shortwave radio, etc.)

A cellular device 200 can be configured with a satellite radio receiver206 coupled with a communication bus 216 for receiving signals fromcommunication satellites 201, a GNSS receiver 107 coupled with bus 216for receiving radio navigation signals from global navigation satellites202 and for deriving a position of cellular device 200 based thereon.Cellular device 200 further comprises an FM radio receiver 208 coupledwith bus 216 for receiving broadcast signals from terrestrial radiobroadcast 203. Other components of cellular device 200 comprise aprocessor 109 coupled with bus 216 for processing information andinstructions, a memory 210 coupled with bus 216 for storing informationand instructions for processor 109. It is noted that memory 210 cancomprise volatile memory and non-volatile memory, as well as removabledata storage media in accordance with various embodiments. Cellulardevice 200 further comprises a cellular transceiver 211 coupled with bus216 for communicating via cellular network 222. Examples of cellularnetworks used by cellular device 200 include, but are not limited toGSM: cellular networks, GPRS cellular networks, GDMA cellular networks,and EDGE cellular networks. Cellular device 200 further comprises adisplay 212 coupled with bus 216. Examples of devices which can be usedas display 212 include, but are not limited to, liquid crystal displays,LED-based displays, and the like. It is noted that display 212 can beconfigured as a touch screen device (e.g., a capacitive touch screendisplay) for receiving inputs from a user as well as displaying data.Cellular device 200 further comprises an audio output 213 coupled withbus 216 for conveying audio information to a user. Cellular device 200further comprises a Wi-Fi transceiver 214 and an inertial measurementunit (IMU) 215 coupled with bus 216. Wi-Fi transceiver 114 may beconfigured to operate on/in compliance with any suitable wirelesscommunication protocol including, but not limited to: Wi-Fi, WiMAX,implementations of the IEEE 802.11 specification, implementations of theIEEE 802.15.4 specification for personal area networks, and a shortrange wireless connection operating in the Instrument Scientific andMedical (ISM) band of the radio frequency spectrum in the 2400-2484 MHzrange (e.g., implementations of the Bluetooth® standard).

Improvements in GNSS/GPS positioning may be obtained by using referencestations with a fixed receiver system to calculate corrections to themeasured pseudoranges in a given geographical region. Since thereference station is located in a fixed environment and its location canbe determined very precisely via ordinary survey methods, a processorassociated with the Reference Station GNSS/GPS receivers can determinemore precisely what the true pseudoranges should be to each satellite inview, based on geometrical considerations. Knowing the orbital positionsvia the GPS almanac as a function of time enables this process, firstproposed in 1983, and widely adopted ever since. The difference betweenthe observed pseudorange and the calculated pseudorange for a givenReference station is called the pseudorange correction. A set ofcorrections for all the global navigation satellites 202 in view iscreated second by second, and stored, and made available as a service,utilizing GPS/GNSS reference stations 220 and correction services 221.The pseudoranges at both the cellular device 200 GPS receiver 107 andthose at the reference stations 220 are time-tagged, so the correctionsfor each and every pseudorange measurement can be matched to the localcell phone pseudoranges. The overall service is often referred to asDifferential GPS, or DGPS. Without any corrections, GNSS/GPS receiversproduce position fixes with absolute errors in position on the order of4.5 to 5.5 m per the GPS SPS Performance Standard, 4^(th) Ed. 2008. InFIG. 2, one or more correction services 221 convey these corrections viaa cellular network 222, or the Internet 223. Internet 223 is in turncoupled with a local Wi-Fi network 224 which can convey the correctionsto cellular device 200 via Wi-Fi transceiver 214. Alternatively,cellular network 222 can convey the corrections to cellular device 200via cellular transceiver 211. In some embodiments, correction services221 are also coupled with a distribution service 225 which conveys thecorrections to an FM radio distributor 226. FM radio distributor 226 canbroadcast corrections as a terrestrial radio broadcast 103. It should beappreciated that an FM signal is being described as a subset of possibleterrestrial radio broadcasts which may be in a variety of bands andmodulated in a variety of manners. In some embodiments, cellular device200 includes one or more integral terrestrial radio antennas associatedwith integrated terrestrial receivers; FM radio receiver 208 is oneexample of such a terrestrial receiver which would employ an integratedantenna designed to operate in the correct frequency band for receivinga terrestrial radio broadcast 103. In this manner, in some embodiments,cellular device 200 can receive the corrections via FM radio receiver208 (or other applicable type of integrated terrestrial radio receiver).In some embodiments, correction services 221 are also coupled with adistribution service 225 which conveys the corrections to a satelliteradio distributor 227. Satellite radio distributor 227 can broadcastcorrections as a broadcast from one or more communications satellites201. In some embodiments, cellular device 200 includes one or moreintegral satellite radio antennas associated with integrated satelliteradio receivers 206. Satellite radio receiver 206 is one example of sucha satellite receiver which would employ an integrated antenna designedto operate in the correct frequency band for receiving a corrections orother information broadcast from communication satellites 201. In thismanner, in some embodiments, cellular device 200 can receive thecorrections via satellite radio receiver 206.

Examples of a correction source that provides pseudorange correctionsare at least correction service 221, FM radio distribution 226, orsatellite radio distributor 227, or a combination thereof. According toone embodiment, a correction source is located outside of the cellulardevice 200.

Examples of image capturing device 240 are a camera, a video camera, adigital camera, a digital video camera, a digital camcorder, a stereodigital camera, a stereo video camera, a motion picture camera, and atelevision camera. The image capturing device 240 may use a lens or be apinhole type device.

The blocks that represent features in FIGS. 1A-2 can be arrangeddifferently than as illustrated, and can implement additional or fewerfeatures than what are described herein. Further, the featuresrepresented by the blocks in FIGS. 1A-2 can be combined in various ways.A cellular device 100, 200 (FIGS. 1A-3) can be implemented usingsoftware, hardware, hardware and software, hardware and firmware, or acombination thereof. Further, unless specified otherwise, variousembodiments that are described as being a part of the cellular device100, 200, whether depicted as a part of the cellular device 100, 200 ornot, can be implemented using software, hardware, hardware and software,hardware and firmware, software and firmware, or a combination thereof.Various blocks in FIGS. 1A-2 refer to features that are logic, such asbut not limited to, 150, 180B, 152, 152A, 152B, 151, 151A-151G, 170B,which can be; implemented using software, hardware, hardware andsoftware, hardware and firmware, software and firmware, or a combinationthereof.

The cellular device 100, 200, according to one embodiment, includeshardware, such as the processor 109, memory 210, and the GNSS chipset170. An example of hardware memory 210 is a physically tangible computerreadable storage medium, such as, but not limited to a disk, a compactdisk (CD), a digital versatile device (DVD), random access memory (RAM)or read only memory (ROM) for storing instructions. An example of ahardware processor 109 for executing instructions is a centralprocessing unit. Examples of instructions are computer readableinstructions for implementing at least the SUPL Client 101 that can bestored on a hardware memory 210 and that can be executed, for example,by the hardware processor 109. The SUPL client 101 may be implemented ascomputer readable instructions, firmware or hardware, such as circuitry,or a combination thereof.

Pseudorange Information

A GNSS receiver 107 (also referred to as a “receiver”), according tovarious embodiments, makes a basic measurement that is the apparenttransit time of the signal from a satellite to the receiver, which canbe defined as the difference between signal reception time, asdetermined by the receiver's clock, and the transmission time at thesatellite, as marked in the signal. This basic measurement can bemeasured as the amount of time shift required to align the C/A-codereplica generated at the receiver with the signal received from thesatellite. This measurement may be biased due to a lack ofsynchronization between the satellite and receiver clock because eachkeeps time independently. Each satellite generates a respective signalin accordance using a clock on board. The receiver generates a replicaof each signal using its own clock. The corresponding biased range, alsoknown as a pseudorange, can be defined as the transit time so measuredmultiplied by the speed of light in a vacuum.

There are three time scales, according to one embodiment. Two of thetime scales are the times kept by the satellite and receiver clocks. Athird time scale is a common time reference, GPS Time (GPST), also knownas a composite time scale that can be derived from the times kept byclocks at GPS monitor stations and aboard the satellites.

Let τ be the transit time associated with a specific code transition ofthe signal from a satellite received at time t per GPST. The measuredapparent range r, called pseudorange, can be determined from theapparent transmit time using equation 1 as follows:

measured pseudorange at (t)=c[arrival time at (t)−emission time at(t−τ)].  Eq. 1

Both t and τ are unknown, and can be estimated. In this discussion ofpseudoranges, measurements from a GPS satellite are dealt with in ageneric way to make the notation simple, making no reference to thesatellite ID or carrier frequency (L1 or L2).

Equations 2 and 3 depict how to relate the time scales of the receiverand the satellite clocks with GPST:

arrival time at (t)=t+receiver clock at (t)  eq. 2

arrival time at (t−τ)=(t−τ)+satellite clock error at (t−τ)  eq. 3

where receiver clock error represents the receiver 304's clock bias 303and satellite clock error represents the bias 301 in the satellite 305'sclock, and both the receiver clock and the satellite clock are measuredrelative to GPST 302, as shown in FIG. 3. Receiver clock error andsatellite clock error represent the amounts by which the satellite 305and receiver 304 clocks are advanced in relation to GPST. The satelliteclock error 301 is estimated by the Control Segment and specified interms of the coefficients of a quadratic polynomial in time. The valuesof these coefficients can be broadcast in the navigation message.

Accounting for the clock biases, the measured pseudorange (eq. 1) can bewritten as indicated in equation 4:

PR(t)=c[t+receiver clock error at (t)−(t−τ+satellite clock error at(t−τ))]+miscellaneous errors at (t)=cτ+c[receiver clock errors at(t)−satellite clock error at (t−τ)]+miscellaneous errors at (t)  eq. 4

where miscellaneous errors represent unmodeled effects, modeling error,and measurement error. The transmit time multiplied by the speed oflight in a vacuum can be modeled as satellite position at (t−τ).Ionosphere error and troposphere error reflect the delays associatedwith the transmission of the signal respectively through the ionosphereand the troposphere. Both ionosphere error and troposphere error arepositive.

For simplicity, explicitly reference to the measurement epoch t has beendropped, and the model has been rewritten for the measured pseudorangeas indicated in equation 5.

PR=r+[receiver clock error−satellite clock error]+ionosphereerror+troposphere error+miscellaneous errors  eq. 5

where PR is the measured pseudorange, r is the true range from thereceiver to the satellite, receiver clock error is the differencebetween the receiver clock and the GPSTIME, satellite clock error is thedifference between the satellite clock and GPSTIME, GPSTIME isultimately determined at the receiver as part of the least squaredsolution determined by the least squares solution 171B so that all clockerrors can be resolved to some level of accuracy as part of the positiondetermination process, and miscellaneous errors include receiver noise,multipath and the like.

At least one source of error is associated with satellite positions inspace. The navigation message in the GPS signal contains Keplerianparameters which define orbital mechanics mathematics and, thus, thepositions of the satellites as a function of time. One component of WAASand RTX™ contains adjustments to these parameters, which form part ofthe constants used in solving for the position fix at a given time.Taking account of the corrections is well-known in the GPS positiondetermining arts.

Ideally, the true range r to the satellite is measured. Instead, what isavailable is PR, the pseudorange, which is a biased and noisymeasurement of r. The accuracy of an estimated position, velocity, ortime, which is obtained from these measurements, depends upon theability to compensate for, or eliminate, the biases and errors.

The range to a satellite is approximately 20,000 kilometers (km) whenthe satellite is overhead, and approximately 26,000 km when thesatellite is rising or setting. The signal transit time varies betweenabout 70 millisecond (ms) and 90 ms. The C/A-code repeats eachmillisecond, and the code correlation process essentially provides ameasurement of pseudo-transmit time modulo 1 ms. The measurement can beambiguous in whole milliseconds. This ambiguity, however, is easilyresolved if the user has a rough idea of his location within hundreds ofkilometers. The week-long P(Y)-code provides unambiguous pseudoranges.

The receiver clocks are generally basic quartz crystal oscillators andtend to drift. The receiver manufacturers attempt to limit the deviationof the receiver clock from GPST, and schedule the typicalonce-per-second measurements at epochs that are within plus or minus 1millisecond (ms) of the GPST seconds. One approach to maintaining thereceiver clock within a certain range of GPST is to steer the receiverclock ‘continuously.’ The steering can be implemented with software. Thesecond approach is to let the clock drift until it reaches a certainthreshold (typically 1 ms), and then reset it with a jump to return thebias to zero.

An example of pseudorange measurements with a receiver using the secondapproach shall now be described in more detail. Assume that there arepseudorange measurements from three satellites which rose about the sametime but were in different orbits. Assume that one comes overhead andstays in view for almost seven hours. Assume that the other two staylower in the sky and could be seen for shorter periods. There arediscontinuities common to all three sets of measurements due to theresetting of the receiver clock. A determination can be made as towhether the receiver clock is running fast or slow, and its frequencyoffset from the nominal value of 10.23 megahertz (MHz) can be estimated.

For more information on pseudorange information, refer to “GlobalPositioning Systems,” by Pratap Misra and Per Enge, Ganga-Jamuna Press,2001; ISBN 0-9709544-0-9.

Position Accuracy Improvements

The pseudorange information processing logic 150 can include varioustypes of logic for improving the position accuracy of the extractedpseudorange information, as described herein. Table 2, as describedherein, depicts various combinations of position accuracy improvementsfor improving extracted pseudorange information, according to variousembodiments. Table 3 also depicts various combinations of positionaccuracy improvements for improving extracted pseudorange information,according to various embodiments.

TABLE 3 Various Combinations of Position Accuracy Improvements forImproving Extracted Pseudorange Information Combination IdentifierOperation Description Accuracy 1 620 (FIG. 6) Extracted Pseudorange 4-5meters (m) Information (EPI) 2 720A (FIG. 7A) EPI + WAAS approx. 1.7 m 3FIG. 7B EPI + reconstructed CPI + <1 m WAAS 4 820A (FIG. 8A) EPI + DGPS~1 m 5 830A (FIG. 8A) EPI + DGPS + WAAS <1 m 6 820B, 822B, EPI +reconstructed CPI + <1 m 830B, 840B DGPS + WAAS FIG. 8B 7 820B, 824B,EPI + real CPI + DGPS + <1 m 830B, 840B WAAS (FIG. 8B) 8 920A (FIG. 9A)EPI + PPP <1 m 9 930A (FIG. 9A) EPI + PPP + DGPS <1 m 10 FIG. 9B EPI +reconstructed CPI + <1 m PPP + DGPS 11 1020 and 1030 EPI + CPI + PPP <<1m (FIG. 10) 12 1040 (FIG. 10) EPI + CPI + PPP + DGPS approx. 10 cm 13EPI + RTK approx. 2-10 cm

Table 3 includes columns for combination identifier, operation,description, and accuracy. The combination identifier column indicatesan identifier for each combination of improvements. The operation columnspecifies operations of various flowcharts in FIGS. 6-10 for thecorresponding combination. The description column specifies variouscombinations of position accuracy improvements that can be applied toextracted pseudorange information (EPI) according to variousembodiments, where examples of position accuracy improvements include,but are not limited to, Wide Area Augmentation System (WAAS) pseudorangecorrections, real carrier phase smoothing (real CPI) information,reconstructed carrier phase smoothing information (reconstructed CPI),Differential GPS (DGPS) pseudorange corrections, and Precise PointPositioning (PPP) processing. The accuracy column specifies levels ofaccuracy provided by the corresponding combination.

Combination 1 is extracted pseudorange information without anyadditional improvements, which provides 4-5 meters of accuracy.Combination 1 is described in Table 3 to provide a comparison with theother combinations 2-13.

According to one embodiment, the SUPL client 101 can also include aposition-accuracy-improvement-determination-logic 180B for determiningthe one or more position accuracy improvements to apply to the extractedpseudorange information based on one or more factors such as cost,quality of service, and one or more characteristics of the cellulardevice. For example, different costs are associated with differentposition accuracy improvements. More specifically, extracted pseudorangeinformation, WAAS and Doppler information are typically free. There is alow cost typically associated with DGPS and real carrier phaseinformation. There is typically a higher cost associated with PPP.Therefore, referring to Table 3, according to one embodiment,combinations 1, 2, and 3 are typically free, combinations 4-7 typicallyare low cost, and combinations 8-12 are typically higher cost.

Various cellular devices have different characteristics that make themcapable of providing different types of position accuracy improvements.For example, one type of cellular device may be capable of providingWAAS but not be capable of providing Doppler information. In anotherexample, some types of cellular devices may be capable of providing DGPSbut not capable of providing PPP. In yet another example, differentactivities may require different levels of improvement. For example,some activities and/or people may be satisfied with 4-5 meters, othersmay be satisfied with 1.7 meters. Yet others may be satisfied with lessthan 1 meter, and still others may only be satisfied with 2 centimeters.Therefore, different users may request different levels of accuracy.

Table 4 depicts sources of the various position accuracy improvements,according to various embodiments.

TABLE 4 Sources of the Various Position Accuracy Improvements PositionAccuracy Improvement Name Source Pseudorange Information extracted fromGNSS chipset WAAS extracted from GNSS chipset or satellite broadcast viaInternet or radio delivery Real Carrier Phase extracted from GNSSchipset Information Doppler for reconstructing extracted from GNSSchipset carrier phase information Differential Global from a referencestation delivered by Positioning System dialing up, wired/wirelessinternet/intranet (DGPS) connection, or by receiving a broadcastsubcarrier modulation concatenated to an FM carrier frequency. DGPS canbe obtained at least from Trimble ® Real Time Kinematic (RTK) from areference station

The first column of Table 4 provides the name of the position accuracyimprovement. The second column of Table 4 specifies the source for thecorresponding position accuracy improvement.

According to various embodiments, a cellular device 100, 200 caninitially provide a position that is within 4-5 meters using, forexample, unimproved extracted pseudorange information and the positioncan continually be improved, using various position accuracyimprovements as described herein, as long as the antennae of thecellular device 100, 200 is clear of obstructions to receive variousposition accuracy improvements.

The following describes various position accuracy improvements andrelated topics in more detail.

Global Navigation Satellite Systems

A Global Navigation Satellite System (GNSS) is a navigation system thatmakes use of a constellation of satellites orbiting the earth to providesignals to a receiver, such as GNSS receiver 107, which estimates itsposition relative to the earth from those signals. Examples of suchsatellite systems are the NAVSTAR Global Positioning System (GPS)deployed and maintained by the United States, the GLObal NAvigationSatellite System (GLONASS) deployed by the Soviet Union and maintainedby the Russian Federation, and the GALILEO system currently beingdeployed by the European Union (EU).

Each GPS satellite transmits continuously using two radio frequencies inthe L-band, referred to as L1 and L2, at respective frequencies of1575.41 MHz and 1227.60 MHz. Two signals are transmitted on L1, one forcivil users and the other for users authorized by the Unites StatesDepartment of Defense (DoD). One signal is transmitted on L2, intendedonly for DoD-authorized users. Each GPS signal has a carrier at the L1and L2 frequencies, a pseudo-random number (PRN) code, and satellitenavigation data.

Two different PRN codes are transmitted by each satellite: A coarseacquisition (C/A) code and a precision (P/Y) code which is encrypted foruse by authorized users. A receiver, such as GNSS receiver 107, designedfor precision positioning contains multiple channels, each of which cantrack the signals on both L1 and L2 frequencies from a GPS satellite inview above the horizon at the receiver antenna, and from these computesthe observables for that satellite comprising the L1 pseudorange,possibly the L2 pseudorange and the coherent L1 and L2 carrier phases.Coherent phase tracking implies that the carrier phases from twochannels assigned to the same satellite and frequency will differ onlyby an integer number of cycles.

Each GLONASS satellite transmits continuously using two radio frequencybands in the L-band, also referred to as L1 and L2. Each satellitetransmits on one of multiple frequencies within the L1 and L2 bandsrespectively centered at frequencies of 1602.0 MHz and 1246.0 MHz. Thecode and carrier signal structure is similar to that of NAVSTAR. A GNSSreceiver designed for precision positioning contains multiple channelseach of which can track the signals from both GPS and GLONASS satelliteson their respective L1 and L2 frequencies, and generate pseudorange andcarrier phase observables from these. Future generations of GNSSreceivers will include the ability to track signals from all deployedGNSSs.

Differential Global Positioning System (DGPS)

Differential GPS (DGPS) utilizes a reference station which is located ata surveyed position to gather data and deduce corrections for thevarious error contributions which reduce the precision of determining aposition fix. For example, as the GPS signals pass through theionosphere and troposphere, propagation delays may occur. Other factorswhich may reduce the precision of determining a position fix may includesatellite clock errors, GPS receiver clock errors, and satelliteposition errors (ephemerides). The reference station receivesessentially the same GPS signals as cellular devices 100, 200 which mayalso be operating in the area. However, instead of using the timingsignals from the GPS satellites to calculate its position, it uses itsknown position to calculate timing. In other words, the referencestation determines what the timing signals from the GPS satellitesshould be in order to calculate the position at which the referencestation is known to be. The difference in timing can be expressed interms of pseudorange lengths, in meters. The difference between thereceived GPS signals and what they optimally should be is used as anerror correction factor for other GPS receivers in the area. Typically,the reference station broadcasts the error correction to, for example, acellular device 100, 200 which uses this data to determine its positionmore precisely. Alternatively, the error corrections may be stored forlater retrieval and correction via post-processing techniques.

DGPS corrections cover errors caused by satellite clocks, ephemeris, andthe atmosphere in the form of ionosphere errors and troposphere errors.The nearer a DGPS reference station is to the receiver 107 the moreuseful the DGPS corrections from that reference station will be.

The system is called DGPS when GPS is the only constellation used forDifferential GNSS. DGPS provides an accuracy on the order of 1 meter or1 sigma for users in a range that is approximately in a few tens ofkilometers (kms) from the reference station and growing at the rate of 1m per 150 km of separation. DGPS is one type of Differential GNSS(DGNSS) technique. There are other types of DGNSS techniques, such asRTK and Wide Area RTK (WARTK), that can be used by high-precisionapplications for navigation or surveying that can be based on usingcarrier phase measurements. It should be appreciated that other DGNSSwhich may utilize signals from other constellations besides the GPSconstellation or from combinations of constellations. Embodimentsdescribed herein may be employed with other DGNSS techniques besidesDGPS.

A variety of different techniques may be used to deliver differentialcorrections that are used for DGNSS techniques. In one example, DGNSScorrections are broadcast over an FM subcarrier. U.S. Pat. No. 5,477,228by Tiwari et al. describes a system for delivering differentialcorrections via FM subcarrier broadcast method, the contents of whichare incorporated herein by reference.

Real-Time Kinematic System

An improvement to DGPS methods is referred to as Real-time Kinematic(RTK). As in the DGPS method, the RTK method, utilizes a referencestation located at determined or surveyed point. The reference stationcollects data from the same set of satellites in view by the cellulardevice 100, 200 in the area. Measurements of GPS signal errors taken atthe reference station (e.g., dual-frequency code and carrier phasesignal errors) and broadcast to one or more cellular devices 100, 200working in the area. The one or more cellular devices 100, 200 combinethe reference station data with locally collected position measurementsto estimate local carrier-phase ambiguities, thus allowing a moreprecise determination of the cellular device 100, 200's position. TheRTK method is different from DGPS methods in that the vector from areference station to a cellular device 100, 200 is determined (e.g.,using the double differences method). In DGPS methods, referencestations are used to calculate the changes needed in each pseudorangefor a given satellite in view of the reference station, and the cellulardevice 100, 200, to correct for the various error contributions. Thus,DGPS systems broadcast pseudorange correction numbers second-by-secondfor each satellite in view, or store the data for later retrieval asdescribed above.

RTK allows surveyors to determine a true surveyed data point in realtime, while taking the data. However, the range of useful correctionswith a single reference station is typically limited to about 70 kmbecause the variable in propagation delay (increase in apparent pathlength from satellite to a receiver of the cellular device 100, 200, orpseudo range) changes significantly for separation distances beyond 70km. This is because the ionosphere is typically not homogeneous in itsdensity of electrons, and because the electron density may change basedon, for example, the sun's position and therefore time of day.

Thus for surveying or other positioning systems which must work overlarger regions, the surveyor must either place additional base stationsin the regions of interest, or move his base stations from place toplace. This range limitation has led to the development of more complexenhancements that have superseded the normal RTK operations describedabove, and in some cases eliminated the need for a base station GPSreceiver altogether. This enhancement is referred to as the “NetworkRTK” or “Virtual Reference Station” (VRS) system and method.

FIG. 4 depicts a flowchart 400 for determining an RTK position solution,according to one embodiment. At 410, the method begins. The inputs tothe method are reference station network or VRS corrections 412 and GNSSpseudorange plus carrier phase information from the cellular device 414.At 420, reference corrections and cellular device data are synchronizedand corrections are applied to the GNSS data for atmospheric models andso on. The output of 420 is synchronized GNSS data 422, which isreceived by operation 430. At 430, position, carrier phase ambiguitiesin floating point, and nuisance parameters are estimated. The output 432of 430 is user position plus carrier phase ambiguities in floatingpoint. Operation 440 receives the output 432 and produces improveduser-position estimates using the integer-nature of carrier phaseambiguities. The output 442 of 440 is an RTK position solution, whichcan be used according to various embodiments. The method ends at 450.

Network RTK

Network RTK typically uses three or more GPS reference stations tocollect GPS data and extract information about the atmospheric andsatellite ephemeris errors affecting signals within the network coverageregion. Data from all the various reference stations is transmitted to acentral processing facility, or control center for Network RTK. Suitablesoftware at the control center processes the reference station data toinfer how atmospheric and/or satellite ephemeris errors vary over theregion covered by the network.

The control center computer processor then applies a process whichinterpolates the atmospheric and/or satellite ephemeris errors at anygiven point within the network coverage area and generates a pseudorange correction comprising the actual pseudo ranges that can be used tocreate a virtual reference station. The control center then performs aseries of calculations and creates a set of correction models thatprovide the cellular device 100, 200 with the means to estimate theionospheric path delay from each satellite in view from the cellulardevice 100, 200, and to take account other error contributions for thosesame satellites at the current instant in time for the cellular device100, 200's location.

The cellular device 100, 200 is configured to couple a data-capablecellular telephone to its internal signal processing system. The useroperating the cellular device 100, 200 determines that he needs toactivate the VRS process and initiates a call to the control center tomake a connection with the processing computer.

The cellular device 100, 200 sends its approximate position, based onraw GPS data from the satellites in view without any corrections, to thecontrol center. Typically, this approximate position is accurate toapproximately 4-7 meters. The user then requests a set of “modeledobservables” for the specific location of the cellular device 100, 200.The control center performs a series of calculations and creates a setof correction models that provide the cellular device 100, 200 with themeans to estimate the ionospheric path delay from each satellite in viewfrom the cellular device 100, 200, and to take into account other errorcontributions for those same satellites at the current instant in timefor the cellular device 100, 200's location. In other words, thecorrections for a specific cellular device 100, 200 at a specificlocation are determined on command by the central processor at thecontrol center and a corrected data stream is sent from the controlcenter to the cellular device 100, 200. Alternatively, the controlcenter may instead send atmospheric and ephemeris corrections to thecellular device 100, 200 which then uses that information to determineits position more precisely.

These corrections are now sufficiently precise that the high performanceposition accuracy standard of 2-3 cm may be determined, in real time,for any arbitrary cellular device 100, 200's position. Thus a GPSenabled cellular device 100, 200's raw GPS data fix can be corrected toa degree that makes it behave as if it were a surveyed referencelocation; hence the terminology “virtual reference station.”

An example of a network RTK system in accordance with embodiments of thepresent invention is described in U.S. Pat. No. 5,899,957, entitled“Carrier Phase Differential GPS Corrections Network,” by Peter Loomis,assigned to the assignee of the present invention and incorporated asreference herein in its entirety.

The Virtual Reference Station method extends the allowable distance fromany reference station to the cellular devices 100, 200. Referencestations may now be located hundreds of miles apart, and corrections canbe generated for any point within an area surrounded by referencestations. However, there are many construction projects where cellularcoverage is not available over the entire physical area underconstruction and survey.

Virtual Reference Stations

To achieve very accurate positioning (to several centimeters or less) ofa terrestrial mobile platform of a cellular device 100, 200, relative ordifferential positioning methods are commonly employed. These methodsuse a GNSS reference receiver located at a known position, in additionto the data from a GNSS receiver 107 on the mobile platform, to computethe estimated position of the mobile platform relative to the referencereceiver.

The most accurate known method uses relative GNSS carrier phaseinterferometry between the GNSS cellular device 100, 200's receiver andGNSS reference receiver antennas plus resolution of integer wavelengthambiguities in the differential phases to achieve centimeter-levelpositioning accuracies. These differential GNSS methods are predicatedon the near exact correlation of several common errors in the cellulardevice 100, 200 and reference observables. They include ionosphere andtroposphere signal delay errors, satellite orbit and clock errors, andreceiver clock errors.

When the baseline length between the mobile platform and the referencereceiver does not exceed 10 kilometers, which is normally considered ashort baseline condition, the ionosphere and troposphere signal delayerrors in the observables from the cellular device 100, 200 andreference receivers are almost exactly the same. These atmospheric delayerrors therefore cancel in the cellular device 100, 200's referencedifferential GNSS observables, and the carrier phase ambiguityresolution process required for achieving centimeter-level relativepositioning accuracy is not perturbed by them. If the baseline lengthincreases beyond 10 kilometers (considered a long baseline condition),these errors at the cellular device 100, 200 and reference receiverantennas become increasingly different, so that their presence in thecellular device 100, 200's-reference differential GNSS observables andtheir influence on the ambiguity resolution process increases. Ambiguityresolution on single cellular device 100, 200's reference receiverbaselines beyond 10 kilometers becomes increasingly unreliable. Thisattribute limits the precise resolution of a mobile platform withrespect to a single reference receiver, and essentially makes itunusable on a mobile mapping platform that covers large distances aspart of its mission, such as an aircraft.

A network GNSS method computes the estimated position of a cellulardevice 100, 200's receiver using reference observables from three ormore reference receivers that approximately surround the cellular device100, 200's receiver trajectory. This implies that the cellular device100, 200's receiver trajectory is mostly contained by a closed polygonwhose vertices are the reference receiver antennas. The cellular device100, 200's receiver 107 can move a few kilometers outside this polygonwithout significant loss of positioning accuracy. A network GNSSalgorithm calibrates the ionosphere and troposphere signal delays ateach reference receiver position and then interpolates and possiblyextrapolates these to the cellular device 100, 200's position to achievebetter signal delay cancellation on long baselines than could be hadwith a single reference receiver. Various methods of signal processingcan be used, however they all yield essentially the same performanceimprovement on long baselines.

Kinematic ambiguity resolution (KAR) satellite navigation is a techniqueused in numerous applications requiring high position accuracy. KAR isbased on the use of carrier phase measurements of satellite positioningsystem signals, where a single reference station provides the real-timecorrections with high accuracy. KAR combines the L1 and L2 carrierphases from the cellular device 100, 200 and reference receivers so asto establish a relative phase interferometry position of the cellulardevice 100, 200's antenna with respect to the reference antenna. Acoherent L1 or L2 carrier phase observable can be represented as aprecise pseudorange scaled by the carrier wavelength and biased by aninteger number of unknown cycles known as cycle ambiguities.Differential combinations of carrier phases from the cellular device100, 200 and reference receivers result in the cancellation of allcommon mode range errors except the integer ambiguities. An ambiguityresolution algorithm uses redundant carrier phase observables from thecellular device 100, 200 and reference receivers, and the knownreference antenna position, to estimate and thereby resolve theseambiguities.

Once the integer cycle ambiguities are known, the cellular device 100,200's receiver 107 can compute its antenna position with accuraciesgenerally on the order of a few centimeters, provided that the cellulardevice 100, 200 and reference antennas are not separated by more than 10kilometers. This method of precise positioning performed in real-time iscommonly referred to as real-time kinematic (RTK) positioning. Theseparation between a cellular device 100, 200 and reference antennasshall be referred to as “cellular device reference separation.”

The reason for the cellular device-reference separation constraint isthat KAR positioning relies on near exact correlation of atmosphericsignal delay errors between the cellular device 100, 200 and referencereceiver observables, so that they cancel in the cellular device 100,200's reference observables combinations (for example, differencesbetween cellular device 100, 200 and reference observables persatellite). The largest error in carrier-phase positioning solutions isintroduced by the ionosphere, a layer of charged gases surrounding theearth. When the signals radiated from the satellites penetrate theionosphere on their way to the ground-based receivers, they experiencedelays in their signal travel times and shifts in their carrier phases.A second significant source of error is the troposphere delay. When thesignals radiated from the satellites penetrate the troposphere on theirway to the ground-based receivers, they experience delays in theirsignal travel times that are dependent on the temperature, pressure andhumidity of the atmosphere along the signal paths. Fast and reliablepositioning requires good models of the spatio-temporal correlations ofthe ionosphere and troposphere to correct for these non-geometricinfluences.

When the cellular device 100, 200 reference separation exceeds 10kilometers, as maybe the case when the cellular device 100, 200 has aGNSS receiver 107 that is a LEO satellite receiver, the atmosphericdelay errors become de-correlated and do not cancel exactly. Theresidual errors can now interfere with the ambiguity resolution processand thereby make correct ambiguity resolution and precise positioningless reliable.

The cellular device 100, 200's reference separation constraint has madeKAR positioning with a single reference receiver unsuitable for certainmobile positioning applications where the mission of the mobile platformof the cellular device 100, 200 will typically exceed this constraint.One solution is to set up multiple reference receivers along the mobileplatform's path so that at least one reference receiver falls within a10 km radius of the mobile platform's estimated position.

Network GNSS methods using multiple reference stations of known locationallow correction terms to be extracted from the signal measurements.Those corrections can be interpolated to all locations within thenetwork. Network KAR is a technique that can achieve centimeter-levelpositioning accuracy on large project areas using a network of referenceGNSS receivers. This technique operated in real-time is commonlyreferred to as network RTK. The network KAR algorithm combines thepseudorange and carrier phase observables from the reference receiversas well as their known positions to compute calibrated spatial andtemporal models of the ionosphere and troposphere signal delays over theproject area. These calibrated models provide corrections to theobservables from the cellular device 100, 200's receiver, so that thecellular device 100, 200's receiver 107 can perform reliable ambiguityresolution on combinations of carrier phase observables from thecellular device 100, 200 and some or all reference receivers. The numberof reference receivers required to instrument a large project area issignificantly less than what would be required to compute reliablesingle baseline KAR solutions at any point in the project area. See, forexample, U.S. Pat. No. 5,477,458, “Network for Carrier PhaseDifferential GPS Corrections,” and U.S. Pat. No. 5,899,957, “CarrierPhase Differential GPS Corrections Network”. See also Liwen Dai et al.,“Comparison of Interpolation Algorithms in Network-Based GPSTechniques,” Journal of the Institute of Navigation, Vol. 50, No. 4(Winter 1003-1004) for a comparison of different network GNSSimplementations and comparisons of their respective performances.

A virtual reference station (VRS) network method is a particularimplementation of a network GNSS method that is characterized by themethod by which it computes corrective data for the purpose of cellulardevice 100, 200's position accuracy improvement. A VRS network methodcomprises a VRS corrections generator and a single-baseline differentialGNSS position generator such as a GNSS receiver 107 with differentialGNSS capability. The VRS corrections generator has as input data thepseudorange and carrier phase observables on two or more frequenciesfrom N reference receivers, each tracking signals from M GNSSsatellites. The VRS corrections generator outputs a single set of Mpseudorange and carrier phase observables that appear to originate froma virtual reference receiver at a specified position (hereafter calledthe VRS position) within the boundaries of the network defined by apolygon (or projected polygon) having all or some of the N referencereceivers as vertices. The dominant observables errors comprising areceiver clock error, satellite clock errors, ionosphere and tropospheresignal delay errors and noise all appear to be consistent with the VRSposition. The single-baseline differential GNSS position generatorimplements a single-baseline differential GNSS position algorithm, ofwhich numerous examples have been described in the literature. B.Hofmann-Wellenhof et al., Global Positioning System: Theory andPractice, 5th Edition, 1001 (hereinafter “Hofmann-Wellenhof [1001]”),gives comprehensive descriptions of different methods of differentialGNSS position computation, ranging in accuracies from one meter to a fewcentimeters. The single-baseline differential GNSS position algorithmtypically computes differences between the cellular device 100, 200 andreference receiver observables to cancel atmospheric delay errors andother common mode errors such as orbital and satellite clock errors. TheVRS position is usually specified to be close to or the same as theroving receiver's estimated position so that the actual atmosphericerrors in the cellular device 100, 200 receiver 107's observablesapproximately cancel the estimated atmospheric errors in the VRSobservables in the cellular device 100, 200's reference observablesdifferences.

The VRS corrections generator computes the synthetic observables at eachsampling epoch (typically once per second) from the geometric rangesbetween the VRS position and the M satellite positions as computed usingwell-known algorithms such as those given in IS-GPS-200G interfacespecification tilted “Naystar GPS Space Segment/Navigation UserInterfaces,” and dated 5 Sep. 2012. It estimates the typical pseudorangeand phase errors comprising receiver clock error, satellite clockerrors, ionospheric and tropospheric signal delay errors and noise,applicable at the VRS position from the N sets of M observablesgenerated by the reference receivers, and adds these to the syntheticobservables.

A network RTK system operated in real time requires each GNSS referencereceiver to transmit its observables to a network server computer thatcomputes and transmits the corrections and other relevant data to theGNSS cellular device 100, 200's receiver 107. The GNSS referencereceivers, plus hardware to assemble and broadcast observables, aretypically designed for this purpose and are installed specifically forthe purpose of implementing the network. Consequently, those receiversare called dedicated (network) reference receivers.

An example of a VRS network is designed and manufactured by TrimbleNavigation Limited, of Sunnyvale, Calif. The VRS network as delivered byTrimble includes a number of dedicated reference stations, a VRS server,multiple server-reference receiver bi-directional communicationchannels, and multiple server-cellular-device-bi-directional datacommunication channels. Each server-cellular device bi-directionalcommunication channel serves one cellular device 100, 200. The referencestations provide their observables to the VRS server via theserver-reference receiver bi-directional communication channels. Thesechannels can be implemented by a public network such as the Internet.The bi-directional server-cellular-device communication channels can beradio modems or cellular telephone links, depending on the location ofthe server with respect to the cellular device 100, 200.

The VRS server combines the observables from the dedicated referencereceivers to compute a set of synthetic observables at the VRS positionand broadcasts these plus the VRS position in a standard differentialGNSS (DGNSS) message format, such as one of the RTCM (Radio TechnicalCommission for Maritime Services) formats, an RTCA (Radio TechnicalCommission for Aeronautics) format or a proprietary format such as theCMR (Compact Measurement Report) or CMR+ format which are messagingsystem communication formats employed by Trimble Navigation Limited.Descriptions for numerous of such formats are widely available. Forexample, RTCM Standard 10403.1 for DGNSS Services—Version 3, publishedOct. 26, 2006 (and Amendment 2 to the same, published Aug. 31, 2007) isavailable from the Radio Technical Commission for Maritime Services,1800 N. Kent St., Suite 1060, Arlington, Va. 22209. The syntheticobservables are the observables that a reference receiver located at theVRS position would measure. The VRS position is selected to be close tothe cellular device 100, 200's estimated position so that the cellulardevice 100, 200's VRS separation is less than a maximum separationconsidered acceptable for the application. Consequently, the cellulardevice 100, 200 receiver 107 must periodically transmit its approximateposition to the VRS server. The main reason for this particularimplementation of a real-time network RTK system is compatibility withRTK survey GNSS receivers that are designed to operate with a singlereference receiver.

Descriptions of the VRS technique are provided in U.S. Pat. No.6,324,473 of (hereinafter “Eschenbach”) (see particularly col. 7, line21 et seq.) and U.S. Patent application publication no. 2005/0064878, ofB. O'Meagher (hereinafter “O'Meagher”), which are assigned to TrimbleNavigation Limited; and in H. Landau et al., Virtual Reference Stationsversus Broadcast Solutions in Network RTK, GNSS 2003 Proceedings, Graz,Austria (2003); each of which is incorporated herein by reference.

The term “VRS”, as used henceforth in this document, is used asshorthand to refer to any system or technique which has thecharacteristics and functionality of VRS described or referenced hereinand is not necessarily limited to a system from Trimble Navigation Ltd.Hence, the term “VRS” is used in this document merely to facilitatedescription and is used without derogation to any trademark rights ofTrimble Navigation Ltd. or any subsidiary thereof or other relatedentity.

Precise Positioning Point (PPP)

Descriptions of a Precise Point Positioning (PPP) technique are providedin U.S. Patent application publication 20110187590, of Leandro, which isassigned to Trimble Navigation Limited and is incorporated herein byreference. Trimble Navigation Limited has commercialized a version ofPPP corrections which it calls RTX™. PPP corrections can be anycollection of data that provides corrections from a satellite in space,clock errors, ionosphere or troposphere, or a combination thereof.According to one embodiment, PPP corrections can be used in instead ofWAAS or RTX™.

The term Precise Point Positioning (PPP), as used henceforth in thisdocument, is used as shorthand to refer to any system or technique whichhas the characteristics and functionality of PPP described or referencedherein and is not necessarily limited to a system from TrimbleNavigation Ltd. Hence, the term “PPP” is used in this document merely tofacilitate description and is used without derogation to any trademarkrights of Trimble Navigation Ltd. or any subsidiary thereof or otherrelated entity. Techniques for generating PPP corrections are well knownin the art. In general, a PPP system utilizes a network (which may beglobal) of GNSS reference receivers tracking navigation satellites suchas GPS and GLONASS satellites and feeding data back to a centralizedlocation for processing. At the centralized location, the precise orbitsand precise clocks of all of the tracked navigation satellites aregenerated and updated in real time. A correction stream is produced bythe central location; the correction stream contains the orbit and clockinformation. This correction stream is broadcast or otherwise providedto GNSS receivers, such as a GNSS receiver 107, in the field(conventionally by satellite service or cellular link). Correctionsprocessors in the GNSS receivers utilize the corrections to producecentimeter level positions after a short convergence time (e.g., lessthan 30 minutes). A main difference between PPP and VRS is that PPPnetworks of reference receivers are typically global while VRS networksmay be regional or localized with shorter spacing between the referencestations in a VRS network.

Wide Area Augmentation System (WAAS)

Wide Area Augmentation System (WAAS) corrections are corrections ofsatellite position and their behavior. WAAS was developed by the FederalAviation Administration (FAA). WAAS includes a network of referencestations that are on the ground located in North America and Hawaii. Thereference stations transmit their respective measurements to masterstations which queue their respective received measurements. The masterstations transmit WAAS corrections to geostationary WAAS satellites,which in turn broadcast the WAAS corrections back to earth wherecellular devices 100, 200 that include WAAS-enabled GPS receivers canreceive the broadcasted WAAS corrections. According to one embodiment,the GNSS receiver 107 is a WAAS-enabled GPS receiver. The WAAScorrections can be used to improve the accuracy of the respectivecellular devices 100, 200′ positions, for example, by applying the WAAScorrections to extracted pseudoranges. WAAS operation and implementationis well known in the art.

Real Carrier Phase Information

According to one embodiment, a GNSS chipset 170 provides real carrierphase information (also referred to as “actual carrier phaseinformation”). The cellular device 100, 200 can extract real carrierphase information from the GNSS chipset 170 in a manner similar toextracting pseudorange information from the GNSS chipset 170, where theextracted carrier phase information is for use elsewhere in the cellulardevice 100, 200 outside of the GNSS chipset 170 as described herein, forexample, with flowchart 600 of FIG. 6.

FIG. 5A is a flowchart 500A of a method for performing a carrier phasesmoothing operation using real carrier phase information, according toone embodiment. In various embodiments, carrier phase smoothing logic152 may be implemented by either a range domain hatch filter, or aposition domain hatch filter, or by any of other implementations knownin the literature. The range domain hatch filter method is described inU.S. Pat. No. 5,471,217 by Hatch et al., entitled “Method and Apparatusfor Smoothing Coded Measurements in a Global Positioning SystemReceiver,” filed Feb. 1, 1993, incorporated by reference herein, and theHatch paper entitled “The synergism of GPS code and carriermeasurements,” published in the Proceedings of the Third InternationalGeodetic symposium on satellite Doppler Positioning, New Mexico, 1982:1213-1232. See also p 45 of the Master's Thesis by Sudha NeelimaThipparthi entitled “Improving Positional Accuracy using CarrierSmoothing Techniques in Inexpensive GPS Receivers,” MSEE thesis, NewMexico State University, Las Cruces, N. Mex., February 2004.

The filtering/processing described herein lies in the family of errorsin pseudorange processing that affect code and carrier measurements inthe same way. In various embodiments, the code phase pseudorangemeasurements are “disciplined” by subtracting out a more constantequivalent pseudorange-like distance measurement derived from thecarrier phase. Next, a filtering on the net subtracted signal isperformed which allows various embodiments to eliminate multipathinduced errors in the raw, and corrected, pseudorange data. This methoddoes not deal with ionospheric effects, according to one embodiment.

In operation 501A of FIG. 5A, extracted pseudorange information andcarrier phases for a first epoch are collected. In one embodiment, theseextracted pseudorange information and carrier phases are received atcarrier phase smoothing logic 152 from the GNSS receiver 107.

In operation 502A of FIG. 5A, pseudorange corrections are collected andapplied to the first set of extracted pseudoranges collected inoperation 501A. In one embodiment, these corrections themselves may besmoothed at the reference receiver (e.g., at GPS/GNSS reference stations220) so that the delivered pseudorange corrections themselves are lessnoisy. Smoothing the pseudorange corrections derived at the GPS/GNSSreference stations 220 using the same carrier phase method of flowchart500A can vastly improve the quality of the delivered pseudorangecorrections delivered to cellular device 100, 200 for use by a positiondetermination processor (e.g., GNSS receiver 107 or pseudorangeinformation processing logic 150). Such corrected pseudoranges that arealso smoothed may be used by the cellular device 100, 200 and fetched ifavailable.

In operation 503A of FIG. 5A, delta carrier phase measurements for thesame epoch are created using real carrier phase information. Inaccordance with various embodiments, this replicates creating a seconddistance measurement, similar to the reconstructed carrier phaseinformation, based on integrated Doppler Shift.

In operation 504A of FIG. 5A, the delta carrier phase measurements aresubtracted from the corrected extracted pseudoranges. In accordance withvarious embodiments, this provides a fairly constant signal for thatepoch and is equivalent to the corrected extracted pseudorange at thestart of the integration interval. In accordance with variousembodiments, this is referred to as a “disciplining” step that smoothesout the corrected extracted pseudorange signal and therefore reduces theinstant errors in the later-computed position fixes.

In operation 505A of FIG. 5A, the signal is filtered after thesubtraction of operation 504A to reduce noise. In accordance with oneembodiment, this is performed by averaging the carrier phase“yardsticks” over a series of epochs.

In operation 506A of FIG. 5A, the delta carrier phase measurements fromthe real carrier phase processing operation is added back into thefiltered signal of operation 505A.

In operation 507A of FIG. 5A, the new filtered and corrected extractedpseudorange signal is processed, for example, at the pseudorangeinformation processing logic 150, to derive a position fix 172B.

Reconstructing Carrier Phase Information Based on Doppler Shift

Carrier Phase Information can be reconstructed (referred to herein as“reconstructed carrier phase”) based on Doppler Shift. Doppler Shift isthe change in frequency of a periodic event (also known as a “wave”)perceived by an observer that is moving relative to a source of theperiodic event. For example, Doppler shift refers to the change inapparent received satellite signal frequency caused by the relativemotion of the satellites as they either approach the cellular device100, 200 or recede from it. Thus any measurement of Doppler frequencychange is similar to differentiating carrier phase. It is thereforepossible to reconstruct the carrier phase by integrating the Dopplershift data. In an embodiment, the GNSS chipset 170 of GNSS receiver 107may provide Doppler information it determines through other means. ThisDoppler frequency shift information or “Doppler” may be collected ateach GPS timing epoch (e.g., one second) and integrated over a sequenceof the one-second epochs, to produce a model of carrier phase. ThisDoppler-derived carrier phase model may be substituted for the realcarrier phase data, and used in the same manner as shown in the flowchart for carrier phase smoothing of FIG. 5A. Doppler Shift signalprocessing is well known in the art.

FIG. 5B is a flowchart 500B of a method for generating reconstructedcarrier phase information (also referred to as a “Doppler-derivedcarrier phase model”) based on Doppler Shift, according to oneembodiment. In accordance with one embodiment, method of flowchart 500Bis implemented at GPS/GNSS reference stations and the modeled carrierphase is provided to cellular device 100, 200 via one of thecommunication networks described above.

In operation 501B of FIG. 5B, Doppler information from a GNSS receiver107 of a GNSS chipset 170 is received bypseudorange-carrier-phase-smoothing-logic 152.

In operation 502B of FIG. 5B, a series of Doppler information isintegrated. As described above, Doppler frequency shift information maybe collected at each GPS timing epoch (e.g., one second) and stored foruse in producing a model of carrier phase.

In operation 503B of FIG. 5B, a model of carrier phase is created basedon integrated Doppler information. As discussed above with reference tooperation 502B, a series of Doppler information for a plurality oftiming epochs is integrated. In one embodiment, this Doppler informationis integrated over a sequence of the one-second epochs, to produce amodel of carrier phase. The sequence may include 10-100 epochs, orseconds. The model of carrier phase smoothing is used as thereconstructed carrier phase information.

In operation 504B of FIG. 5B, the modeled carrier phase, which is alsoreferred to as “reconstructed carrier phase information”, is supplied topseudorange-carrier-phase-smoothing-logic 152. As described above,method of flowchart 500B can be implemented at GPS/GNSS referencestations 220 and the reconstructed carrier phase information can then bebroadcast to cellular device 100, 200.

Method of Extracting Pseudorange Information

FIG. 6 depicts a flowchart 600 of a method of extracting pseudorangeinformation using a cellular device, according to one embodiment.

At 610, the method begins.

At 620, the cellular device 100, 200 accesses the GNSS chipset 170embedded within the cellular device 100, 200 where the GNSS chipset 170calculates pseudorange information for use by the GNSS chipset 170. Forexample, the GNSS receiver 107 can perform GPS measurements to deriveraw measurement data for a position of the cellular device 100. The rawmeasurement data provides an instant location of the cellular device100. The GNSS chipset 170 calculates pseudorange information that is foruse by the GNSS chipset 170. According to one embodiment, the rawmeasurement data is the pseudorange information that will be extracted.Examples of pseudorange information are uncorrected pseudorangeinformation, differential GNSS corrections, high precision GNSSsatellite orbital data, GNSS satellite broadcast ephemeris data, andionospheric projections.

A chipset accessor logic 141, according to one embodiment, is configuredfor accessing the GNSS chipset 170. According to one embodiment, thechipset accessor logic 141 is a part of an SUPL client 101.

The pseudorange information can be obtained from the processor 172 ofthe GNSS receiver 107 using a command. The GNSS chipset 170 may bedesigned, for example, by the manufacturer of the GNSS chipset 170, toprovide requested information, such as pseudorange information, inresponse to receiving the command. The pseudorange information may beextracted from the GNSS chipset 170 using the command that themanufacturer has designed the GNSS chipset 170 with. For example,according to one embodiment, the GNSS chipset 170 is accessed using anoperation that is a session started with a message that is an improvedaccuracy Secure User Platform Location (SUPL) start message or a highprecision SUPL INIT message. According to one embodiment, the message isa custom command that is specific to the GNSS chipset 170 (also referredto as “a GNSS chipset custom command”) and the improved accuracy SUPLclient 101 can access to the raw measurements of the GNSS chipset 170.

Examples of chipset manufacturers include Qualcomm, Texas Instruments,FastraX, Marvel, SIRF, Trimble, SONY, Furuno, Nemerix, Phillips, andXEMICS, to name a few.

At 630, the cellular device 100, 200 extracts the pseudorangeinformation from the GNSS chipset 170 for use elsewhere in the cellulardevice 100, 200 outside of the GNSS chipset 170. For example,pseudorange information extractor logic 142 may be associated with aworker thread of the SUPL client 101. The worker thread associated withthe SUPL client 101 can monitor the raw measurements delivered by theGNSS chipset 170 into the GNSS chipset 170's memory buffers, cache theraw measurements and use the raw measurements to determine a positionfix. The pseudorange information extractor logic 142 and the pseudorangeinformation processing logic 150 can be associated with the workerthread. For example, the pseudorange information extractor logic 142 cancache the raw measurements and the pseudorange information processinglogic 150 can determine the location.

According to one embodiment, the raw measurement data is the pseudorangeinformation that is extracted. According to one embodiment, the rawmeasurement data is pseudorange information that is calculated by theGNSS chipset 170 and is only for use by the GNSS chipset 170.

According to one embodiment, a determining position fix logic 170B mayperform a least squares solution 171B on the extracted pseudorangeinformation prior to transmitting the output to the pseudorangeinformation bridger logic 143. According to another embodiment, theextracted pseudorange information is improved using various embodimentsdescribed in FIGS. 7A-10 prior to performing a least squares solution171B, as will be described herein.

Methods of Improving Position Accuracy of Extracted PseudorangeInformation

The extracted pseudorange information without further improvements canbe used to provide an instant location, as described herein. Theextracted pseudorange information can be improved by applying positionaccuracy improvements that include, but are not limited to, thosedepicted in Tables 2 and 3. The instant location or the improvedlocation can be communicated to location manager logic 161, as discussedherein, that displays the instant location or the improved location withrespect to a map.

FIG. 7A depicts a flowchart 700A of a method of improving the positionaccuracy using one or more position accuracy improvements, according toone embodiment.

At 710A, the method begins.

At 720A, the pseudorange-correction-logic 151 provides Wide AreaAugmentation System (WAAS) corrected pseudoranges by applying WAAScorrections to the extracted pseudorange information. For example, thepseudorange-correction-logic 151 receives the extracted pseudorangeinformation that was extracted from the GNSS chipset 170 at 630 of FIG.6. The cellular device 100, 200 receives the WAAS corrections, asdescribed herein, and provides the WAAS corrections to thepseudorange-correction-logic 151. The pseudorange-correction-logic 151provides Wide Area Augmentation System (WAAS) corrected pseudoranges byapplying the received WAAS corrections to the extracted pseudorangeinformation.

At 730A the method ends.

FIG. 7B depicts a flowchart 700B of a method of improving the positionaccuracy using one or more position accuracy improvements, according toone embodiment.

At 710B, the method begins.

At 720B, the pseudorange-carrier-phase-smoothing-logic 152 providessmoothed pseudorange information by performing pseudorange smoothing onthe extracted pseudorange information based on carrier phaseinformation. For example, if real carrier phase information isavailable, the cellular device 100, 200 can extract it as discussedherein. Otherwise, the cellular device 100, 200 can derive reconstructedcarrier phase information as described herein and provide thereconstructed carrier phase information to thepseudorange-carrier-phase-smoothing-logic 152. Thepseudorange-carrier-phase-smoothing-logic 152 can receive the extractedpseudorange information that was extracted from the GNSS chipset 170 at630 of FIG. 6. The pseudorange-carrier-phase-smoothing-logic 152 canapply either the real carrier phase information or the real carrierphase information to the extracted pseudorange information to providesmoothed pseudorange information.

At 730B, a position fix is determined based on the smoothed pseudorangeinformation and WAAS pseudorange corrections. For example, thepseudorange-correction-logic 151 receives the smoothed pseudorangeinformation and receives WAAS pseudorange corrections and determines aposition fix based on the smoothed pseudorange information and the WAASpseudorange corrections.

At 740B, the method ends.

According to one embodiment, a determining position fix logic 170B mayperform a least squares solution 171B on the output of flowchart 700Aand 700B prior to transmitting the output to the pseudorange informationbridger logic 143.

FIG. 8A depicts a flowchart 800A of a method of improving the positionaccuracy using one or more position accuracy improvements, according toone embodiment.

At 810A, the method begins.

At 820A, the pseudorange-correction-logic 151 provides DifferentialGlobal Positioning System (DGPS) corrected pseudoranges by applying DGPScorrections to the extracted pseudorange information.

For example, the pseudorange-correction-logic 151 receives the extractedpseudorange information that was extracted from the GNSS chipset 170 at630 of FIG. 6. The cellular device 100, 200 receives the DGPScorrections as described herein and provides the DGPS corrections to thepseudorange-correction-logic 151. The pseudorange-correction-logic 151provides Differential Global Positioning System (DGPS) correctedpseudoranges by applying the received DGPS corrections to the extractedpseudorange information.

At 830A, the pseudorange-correction-logic 151 provides WAAS-DGPScorrected pseudoranges by applying Wide Area Augmentation System (WAAS)to the DGPS corrected pseudoranges.

For example, the pseudorange-correction-logic 151 accesses the DGPScorrected pseudoranges determined at 820A of FIG. 8A. The cellulardevice 100, 200 receives the WAAS corrections as described herein andprovides the WAAS corrections to the pseudorange-correction-logic 151.The pseudorange-correction-logic 151 provides WAAS-DGPS correctedpseudoranges by applying Wide Area Augmentation System (WAAS) to theDGPS corrected pseudoranges.

At 840A, the method ends.

FIG. 8B depicts a flowchart 800B of a method of improving the positionaccuracy using one or more position accuracy improvements, according toone embodiment.

At 810B, the method begins.

At 820B, a position determination decision is made as to whether toproceed to 822B or 824B. For example, at operation 820B, the positionaccuracy improvement determination logic 180B can determine whether toproceed to 822B or 824B as discussed herein.

At 830B, DGPS corrected smoothed pseudoranges are provided by applyingcorrections to the smoothed pseudorange information. For example, thepseudorange-correction-logic 151 can provide DGPS corrected smoothedpseudoranges by applying DGPS corrections to the smoothed pseudorangesdetermined at either 822B or 824B.

At 840B, WAAS-DGPS corrected smoothed pseudoranges are provided byapplying WAAS to the DGPS corrected smoothed pseudoranges. For example,the pseudorange-correction-logic 151 can provide WAAS-DGPS correctedsmoothed pseudoranges by applying WAAS corrections to the DGPS correctedsmoothed pseudoranges.

At 850B, the method ends.

According to one embodiment, a determining position fix logic 170B mayperform a least squares solution 171B on the output of flowcharts 800Aor 800B prior to transmitting the output to the pseudorange informationbridger logic 143.

FIG. 9A depicts a flowchart 900A of a method of improving the positionaccuracy using one or more position accuracy improvements, according toone embodiment.

At 910A, the method begins.

At 920A, DGPS corrected pseudoranges are determined by applying DGPSpseudorange corrections to extracted pseudorange information. Forexample, the pseudorange-correction-logic 151 receives extractedpseudorange information from the pseudorange information extractor logic142 and applies the DGPS pseudorange corrections to the extractedpseudorange information.

At 930A, the pseudorange-correction-logic 151 can determine a positionfix based on the DGPS corrected pseudoranges and PPP corrections.

At 940A, the method ends.

FIG. 9B depicts a flowchart 900B of a method of improving the positionaccuracy using one or more position accuracy improvements, according toone embodiment.

At 910B, the method begins.

At 920B, smoothed pseudorange information is provided by performingpseudorange smoothing on the extracted pseudorange information usingcarrier phase information. For example, thepseudorange-carrier-phase-smoothing-logic 152 provides smoothedpseudorange information by performing pseudorange smoothing on theextracted pseudorange information, which can be obtained as discussedherein, based on carrier phase information. If real carrier phaseinformation is available, the cellular device 100, 200 can extract thereal carrier phase information, as discussed herein. Otherwise, thecellular device 100, 200 can derive reconstructed carrier phaseinformation, as described herein, and provide the reconstructed carrierphase information to the pseudorange-carrier-phase-smoothing-logic 152.

At 930B, DGPS corrected smoothed pseudoranges are provided by applyingDGPS pseudorange corrections to the smoothed pseudorange information.For example, the pseudorange-correction-logic 151 can receive thesmoothed pseudorange information from thepseudorange-carrier-phase-smoothing-logic 152. Thepseudorange-correction-logic 151 can determine the corrected smoothedpseudoranges by applying DGPS pseudorange corrections to the smoothedpseudorange information.

At 940B, a position fix can be determined based on the DGPS correctedsmoothed pseudoranges and PPP corrections. For example, thepseudorange-correction-logic 151 can determine a position fix based onthe DGPS corrected smoothed pseudoranges and PPP corrections.

At 950B, the method ends.

According to one embodiment, a determining position fix logic 170B mayperform a least squares solution 171B on the output of flowcharts 900Aand 900B prior to transmitting the output to the pseudorange informationbridger logic 143.

FIG. 10 depicts a flowchart 1000 of a method of improving the positionaccuracy using one or more position accuracy improvements, according toone embodiment.

At 1010, the method begins.

At 1020, the pseudorange-carrier-phase-smoothing-logic 152 smoothes theextracted pseudorange information based on carrier phase smoothing. Forexample, the pseudorange-carrier-phase-smoothing-logic 152 receivesextracted pseudorange information from the pseudorange informationextractor logic 142 and receives carrier phase information, which may beeither real carrier phase information or reconstructed carrier phaseinformation, as described herein. Thepseudorange-carrier-phase-smoothing-logic 152 smoothes the extractedpseudorange information based on carrier phase smoothing.

At 1030, the PPP logic 151C provides a smoothed improved accuracyposition fix by performing Precise Point Positioning (PPP) processing onthe smoothed extracted pseudorange information. For example, the PPPlogic 151C receives the smoothed extracted pseudorange informationprovided by the pseudorange-carrier-phase-smoothing-logic 152 at 1020.The PPP logic 151C provides a smoothed improved accuracy position fix byperforming Precise Point Positioning (PPP) processing on the smoothedextracted pseudorange information

At 1040, the pseudorange-correction-logic 151 can optionally correct thesmoothed improved accuracy position fix by applying Differential GlobalPositioning System (DGPS) corrections to the smoothed improved accuracyposition fix. For example, pseudorange-correction-logic 151 receives thesmoothed improved accuracy position fix provided by the PPP logic 151Cat 1030. The pseudorange-correction-logic 151 receives DGPS correctionsas described herein. The pseudorange-correction-logic 151 corrects thesmoothed improved accuracy position fix by applying Differential GlobalPositioning System (DGPS) corrections to the smoothed improved accuracyposition fix, thus, providing a corrected smoothed improved accuracyposition fix. Operation 1040 is optional, according to one embodiment.

At 1050, the method ends.

According to one embodiment, a determining position fix logic 170B mayperform a least squares solution 171B on the output of flowchart 1000prior to transmitting the output to the pseudorange information bridgerlogic 143.

FIG. 11 depicts a flowchart 1100 of a method of accessing and processingextracted pseudorange information, according to one embodiment.

At 1110, various types of information can be accessed. Examples ofaccessing are extracting 1112 information and receiving 1114information. Unsmoothed uncorrected pseudorange information can beextracted at 1112A, WAAS corrections can be extracted at 1112B, SBAScorrections can be extracted at 1112E, Doppler shift can be extracted at1112C, and carrier phase measurements can be extracted at 1112D.“Accessing” and “obtaining” can be used interchangeably. Table 1 depictstypes of information that can be extracted at operation 1112 from theGNSS chipset 170 and types of information that are received at operation1114 instead of being extracted. However, various embodiments are notlimited to the types of information that can be extracted or receiveddepicted in Table 1.

The received or extracted information or a combination thereof, can beprocessed at 1120.

What or whether to apply position accuracy improvements can bedetermined at 1160, for example, by the position accuracy improvementdetermination logic 180B. Examples of position accuracy improvements arereal carrier phase information, reconstructed carrier phase information,WAAS, SBAS, DGPS, PPP, RTK, VRS and RTX™ corrections. The determinationlogic 180B can determine whether one or more and in what order logics152A, 152B, 151A-151F are performed, according to one embodiment. Tables2 and 3 are examples of carrier phase information or corrections or acombination thereof, that the position accuracy improvementdetermination logic 180B may determine, as discussed herein.

The information can be smoothed at 1130. Examples of smoothing 1130 arereal carrier phase smoothing 1132 and reconstructed carrier phasesmoothing 1134.

Either unsmoothed information or smoothed information can be correctedat 1140. For example, unsmoothed information from 1110 or smoothedinformation from 1130 can be corrected at 1140. Examples of correctingare SBAS correcting 1140G, WAAS correcting 1140A, DGPS correcting 1140B,PPP correcting 1140C, RTK correcting 1140D, VRS correcting 1140E, andRTX correcting 1140F. The smoothed information or unsmoothed informationcan be corrected using one or more of operations 1140A-1140G. Accordingto one embodiment, WAAS correcting 1140A is an example of SBAScorrecting 1140G.

Unsmoothed information from 1110, smoothed information from 1112,corrected unsmoothed information from 1140 or corrected smoothedinformation from 1140 can be used to determine a position fix 172B at1150, for example, by performing a least squares solution 171B at 1152.The output of flowchart 1100 is a position fix 172B. Table 2 and Table 3depict combinations of information that result in a position fix 172B,according to various embodiments.

According to one embodiment, accessing 1110, extracting 1112, extractingpseudorange information 1112A, extracting SBAS 1112E, extracting WAAS1112B, extracting Doppler 1112C, extracting carrier phase measurement1112D, receiving 1114, smoothing 1130, correcting 1140, determining aposition fix 1150, and performing a least squares solution 1152 can beperformed respectively by logic 110B, 142, 112B-5, 112B-2, 112B-3,112B-4, 114B, 150, 152, 151, and 170B. Real carrier phase smoothing1132, reconstructed carrier phase smoothing 1134, correcting 1140A-1140Gcan be performed respectively by logic 152A, 152B, 151A-151E, 151F,151G.

Any one or more of 1112, 1112A-1112E, 1132, 1134, 1140A-1140G can beperformed. Further, any one or more of 1112, 1112A-1112E, 1112B, 1112C,1112E, 1132, 1134, 1140A-1140G can be performed in various orders.Various embodiments are not limited to just the combinations that aredescribed herein.

According to one embodiment, a Global Navigation Satellite System (GNSS)chipset embedded within the cellular device is accessed at 620 (FIG. 6)where the GNSS chipset calculates pseudorange information for use by theGNSS chipset. The pseudorange information is extracted at 640 (FIG. 6),112 (FIG. 11) from the GNSS chipset for use elsewhere in the cellulardevice outside of the GNSS chipset. The accessing 620 and the extracting640, 1112A can be performed by the cellular device 100, 200 thatincludes hardware 180.

The extracted pseudorange information can be smoothed at 1130. Thesmoothing 1130 can be based on reconstructed carrier phase informationor real carrier phase information. The smoothed pseudorange informationcan be corrected at 1140. Examples of the types of correctedpseudoranges are Wide Area Augmentation System (WAAS), DifferentialGlobal Positioning System (DGPS), Precise Point Positioning (PPP), andReal Time Kinematic (RTK). Pseudorange corrections can be accessed 1110.The corrected pseudorange information can be derived, for example at1140, by applying the pseudorange corrections to the extractedpseudorange information.

FIGS. 4-11 depict flowcharts 400-1100, according to one embodiment.Although specific operations are disclosed in flowcharts 400-1100, suchoperations are exemplary. That is, embodiments of the present inventionare well suited to performing various other operations or variations ofthe operations recited in flowcharts 400-1100. It is appreciated thatthe operations in flowcharts 400-1100 may be performed in an orderdifferent than presented, and that not all of the operations inflowcharts 400-1100 may be performed.

The operations depicted in FIGS. 4-11 transform data or modify data totransform the state of a cellular device 100, 200. For example, byextracting pseudorange information from a GNSS chipset 170 for useelsewhere, the state of the cellular device 100, 200 is transformed froma cellular device that is not capable of determining a position fixitself into a cellular device that is capable of determining a positionfix itself. In another example, operations depicted in flowcharts400-1100 transform the state of a cellular device 100, 200 from notbeing capable of providing an improved accuracy position fix to becapable of providing an improved accuracy position fix.

The above illustration is only provided by way of example and not by wayof limitation. There are other ways of performing the method describedby flowcharts 400-1100.

The operations depicted in FIGS. 4-11 can be implemented as computerreadable instructions, hardware or firmware. According to oneembodiment, hardware associated with a cellular device 100, 200 canperform one or more of the operations depicted in FIGS. 4-11.

Example GNSS Receiver

With reference now to FIG. 12, a block diagram is shown of an embodimentof an example GNSS receiver which may be used in accordance with variousembodiments described herein. In particular, FIG. 12 illustrates a blockdiagram of a GNSS receiver in the form of a general purpose GPS receiver1230 capable of demodulation of the L1 and/or L2 signal(s) received fromone or more GPS satellites. A more detailed discussion of the functionof a receiver such as GPS receiver 1230 can be found in U.S. Pat. No.5,621,416, by Gary R. Lennen, is titled “Optimized processing of signalsfor enhanced cross-correlation in a satellite positioning systemreceiver,” and includes a GPS receiver very similar to GPS receiver 1230of FIG. 12.

In FIG. 12, received L1 and L2 signals are generated by at least one GPSsatellite. Each GPS satellite generates different signal L1 and L2signals and they are processed by different digital channel processors1252 which operate in the same way as one another.

FIG. 12 shows GPS signals (L1=1575.42 MHz, L2=1227.60 MHz) entering GPSreceiver 1230 through a dual frequency antenna 1232. Antenna 1232 may bea magnetically mountable model commercially available from TrimbleNavigation of Sunnyvale, Calif. Master oscillator 1248 provides thereference oscillator which drives all other clocks in the system.Frequency synthesizer 1238 takes the output of master oscillator 1248and generates important clock and local oscillator frequencies usedthroughout the system. For example, in one embodiment frequencysynthesizer 1238 generates several timing signals such as a 1st (localoscillator) signal LO1 at 1400 MHz, a 2nd local oscillator signal LO2 at175 MHz, an SCLK (sampling clock) signal at 25 MHz, and a MSEC(millisecond) signal used by the system as a measurement of localreference time.

A filter/LNA (Low Noise Amplifier) 1234 performs filtering and low noiseamplification of both L1 and L2 signals. The noise figure of GPSreceiver 1230 is dictated by the performance of the filter/LNAcombination. The downconvertor 1236 mixes both L1 and L2 signals infrequency down to approximately 175 MHz and outputs the analog L1 and L2signals into an IF (intermediate frequency) processor 1250. IF processor1250 takes the analog L1 and L2 signals at approximately 175 MHz andconverts them into digitally sampled L1 and L2 inphase (L1 I and L2 I)and quadrature signals (L1 Q and L2 Q) at carrier frequencies 420 KHzfor L1 and at 2.6 MHz for L2 signals respectively.

At least one digital channel processor 1252 inputs the digitally sampledL1 and L2 inphase and quadrature signals. All digital channel processors1252 are typically are identical by design and typically operate onidentical input samples. Each digital channel processor 1252 is designedto digitally track the L1 and L2 signals produced by one satellite bytracking code and carrier signals and to from code and carrier phasemeasurements in conjunction with the GNSS microprocessor system 1254.One digital channel processor 1252 is capable of tracking one satellitein both L1 and L2 channels. Microprocessor system 1254 is a generalpurpose computing device (such as computer system 1000 of FIG. 10) whichfacilitates tracking and measurements processes, providing pseudorangeand carrier phase measurements for a determining position fix logic1258. In one embodiment, microprocessor system 1254 provides signals tocontrol the operation of one or more digital channel processors 1252.According to one embodiment, the GNSS microprocessor system 1254provides one or more of pseudorange information 1272, Doppler Shiftinformation 1274, and real Carrier Phase Information 1276 to thedetermining position fix logic 1258. One or more of pseudorangeinformation 1272, Doppler Shift information 1274, and real Carrier PhaseInformation 1276 can also be obtained from storage 1260. One or more ofthe signals 1272, 1274, 1276 can be conveyed to the cellular device'sprocessor, such as processor 109 (FIG. 1A) that is external to the GNSSchipset 170 (FIG. 1A). Determining position fix logic 1258 performs thehigher level function of combining measurements in such a way as toproduce position, velocity and time information for the differential andsurveying functions, for example, in the form of a position fix 1280.Storage 1260 is coupled with determining position fix logic 1258 andmicroprocessor system 1254. It is appreciated that storage 1260 maycomprise a volatile or non-volatile storage such as a RAM or ROM, orsome other computer readable memory device or media. In someembodiments, determining position fix logic 1258 performs one or more ofthe methods of position correction described herein.

In some embodiments, microprocessor 1254 and/or determining position fixlogic 1258 receive additional inputs for use in receiving correctionsinformation. According to one embodiment, an example of the correctionsinformation is WAAS corrections. According to one embodiment, examplesof corrections information are differential GPS corrections, RTKcorrections, signals used by the previously referenced Enge-Talbotmethod, and wide area augmentation system (WAAS) corrections amongothers.

Although FIG. 12 depicts a GNSS receiver 1130 with navigation signalsL1I, L1Q, L2I, L2Q, various embodiments are well suited differentcombinations of navigational signals. For example, according to oneembodiment, the GNSS receiver 1130 may only have an L1I navigationalsignal. According to one embodiment, the GNSS receiver 1130 may onlyhave L1I, L1Q and L2I.

Various embodiments are also well suited for future navigationalsignals. For example, various embodiments are well suited for thenavigational signal L2C that is not currently generally available.However, there are plans to make it available for non-militaryreceivers.

According to one embodiment, either or both of the accessing logic 110Band the processing logic 150 reside at either or both of the storage1260 and GNSS microprocessor system 1254.

According to one embodiment, the GNSS receiver 1230 is an example of aGNSS receiver 107 (see e.g., FIG. 1A and FIG. 1D). According to oneembodiment, the determining position fix logic 1258 is an example ofdetermining position fix logic 170B (FIG. 1B). According to oneembodiment, position fix 1280 is an example of a position fix 172B (FIG.1B).

Kalman Filtering

FIG. 13 depicts an example Kalman filtering process 1300, according tosome embodiments. It should be appreciated that Kalman filtering is wellknown. As such, FIG. 13 and the associated discussion are utilized onlyto provide a high-level general description. Variations in the describedprocedures will occur during specific implementations of Kalmanfiltering. The extended Kalman filter and the unscented Kalman filterrepresent some of the variations to the basic method. Such variationsare normal and expected. Generally speaking, Kalman filtering is a basictwo-step predictor/corrector modeling process that is commonly usedmodel dynamic systems. A dynamic system will often be described with aseries of mathematical models. Models describing satellites in a GlobalNavigation Satellite System (GNSS) are one example of a dynamic system.Because the position of any satellite and/or the positions of all thesatellites in a system constantly and dynamically change and thesatellites output a signal that can be measured by a GNSS receiver,Kalman filtering can be used in determining positions of the satellites.

A basic Kalman filter implemented using Kalman filtering process 1300typically has at least two major components 1310: states 1311 andcovariances 1312. States 1311 represent variables that are used todescribe a system being modeled, at a particular moment in time.Covariances 1312 are represented in a covariance matrix that describesuncertainty, or lack of confidence, of states 1311 with respect to eachother at that same moment in time. Kalman filtering process 1300 alsohandles noise, or unpredictable variability, in the model. There are twoprinciple types of noise, observation noise 1341 and process noise 1321.A Kalman filter may handle additional noise types, in some embodiments.Process noise 1321 describes noise of the states 1311 as a function oftime. Observation noise 1341 is noise that relates to the actualobservation(s) 1340 (e.g., observed measurements) that are used as aninput/update to Kalman filtering process 1300.

A prediction phase 1320 is the first phase of Kalman filtering process1300. Prediction phase 1320 uses predictive models to propagate states1311 to the time of an actual observation(s) 1340. Prediction phase 1320also uses process noise 1321 and predictive models to propagate thecovariances 1312 to time of the actual observation(s) 1340 as well. Thepropagated states 1311 are used to make predicted observation(s) 1322for the time of actual observation(s) 1340.

A correction phase 1330 is the second phase in the Kalman filteringprocess 1300. During correction phase 1330, Kalman filtering process1300 uses the difference between the predicted observation(s) 1322 andthe actual observation(s) 1340 to create an observation measurementresidual 1331, which may commonly be called the “measurement residual.”Observation noise 1341 can be noise in actual observation(s) 1340 and/ornoise that occurs in the process of taking the actual observation(s)1340. A Kalman gain 1332 is calculated using both the covariances 1312and the observation noise 1341. The states 1311 are then updated usingthe Kalman Gain 1332 multiplied by the observation measurement residual1331. The covariances 1312 are also updated using a function related tothe Kalman gain 1332; for example, in one embodiment where Kalman gainis limited to a value between 0 and 1, this function may be 1 minus theKalman gain. This updating is sometimes referred to as the “covarianceupdate.” In some embodiments, if no actual observation 1340 isavailable, Kalman filtering process 1300 can simply skip correctionphase 1330 and update the states 1311 and covariances 1312 using onlythe information from prediction phase 1320, and then begin again. Usingthe new definitions of the states 1311 and covariances 1312, Kalmanfiltering process 1300 is ready to begin again and/or to be iterativelyaccomplished.

Computer Readable Storage Medium

Unless otherwise specified, any one or more of the embodiments describedherein can be implemented using non-transitory computer readable storagemedium and computer readable instructions which reside, for example, incomputer-readable storage medium of a computer system or like device.The non-transitory computer readable storage medium can be any kind ofphysical memory that instructions can be stored on. Examples of thenon-transitory computer readable storage medium include but are notlimited to a disk, a compact disk (CD), a digital versatile device(DVD), read only memory (ROM), flash, and so on. As described above,certain processes and operations of various embodiments of the presentinvention are realized, in one embodiment, as a series of computerreadable instructions (e.g., software program) that reside withinnon-transitory computer readable storage memory of a cellular device100, 200 (FIGS. 1A-2) and are executed by a hardware processor of thecellular device 100, 200. When executed, the instructions cause acomputer system to implement the functionality of various embodiments ofthe present invention. For example, the instructions can be executed bya central processing unit associated with the cellular device 100, 200.According to one embodiment, the non-transitory computer readablestorage medium is tangible.

Unless otherwise specified, one or more of the various embodimentsdescribed herein can be implemented as hardware, such as circuitry,firmware, or computer readable instructions that are stored onnon-transitory computer readable storage medium. The computer readableinstructions of the various embodiments described herein can be executedby a hardware processor, such as central processing unit, to cause thecellular device 100, 200 to implement the functionality of variousembodiments. For example, according to one embodiment, the SUPL client101 and the operations of the flowcharts 400-1100 depicted in FIGS. 4-11are implemented with computer readable instructions that are stored oncomputer readable storage medium, which can be tangible ornon-transitory or a combination thereof, and can be executed by ahardware processor 109 of a cellular device 100, 200. According to oneembodiment, the non-transitory computer readable storage medium istangible.

GNSS Receiver Positioning System

FIG. 14 is a block diagram of components of a GNSS positioning system1400 in accordance with various embodiments. In FIG. 14 GNSS positioningsystem 1400 comprises receiving component 1402 and a cellular device1410. In accordance with various embodiments, receiving component 1402is a stand-alone device which can be coupled via a wirelesscommunication link with cellular device 1410 to provide improvedreception of GNSS satellite signals, thereby improving the performanceof cellular device 1410 in deriving a position fix. In accordance withvarious embodiments, receiving component 1402 can be coupled with otherdevices and/or articles of clothing using, for example, hook and loop(e.g., Velcro®) strips, adhesives, mechanical fasteners, snap fit,receptacles, or the like, or integrated into those devices such as in adedicated compartment. As will be described in greater detail below, invarious embodiments receiving component 1402 is disposed in such amanner as to provide a better view of the sky which in turn results inbetter reception of radio signals of GNSS satellites which are in view.In accordance with at least one embodiment, receiving component 1402comprises a circularly polarized (CP) GNSS antenna 1403 typicallyrealized in a flat “patch” configuration, but may also be realized in aquadrifiler helix configuration, a GNSS chipset 1404, and a wirelesscommunication component 1405 There are a variety of antenna designswhich can be implemented as GNSS antenna 1403 in accordance with variousembodiments such as, but not limited to, patch antennas, quadrifilerhelix antennas, and planar quadrifiler antennas. In typical GNSSantennas currently used in cellular devices, the GNSS antenna is usuallyconfigured for linear polarization and not a circularly polarizeddesign. This results in a significant loss of signal from orbiting GNSSsatellites, at least 3 dB. However, receiving component 1402 utilizes acircularly polarized GNSS antenna such as circularly polarized GNSSantenna 1403 to provide better signal reception than would typically beexhibited by a cellular device. In various embodiments, GNSS chipset1404 comprises the GNSS chipset of the type that may be found in acellular telephone, or the GNSS chipset of a dedicated GNSS handhelddata collector. In other words, in accordance with one embodiment, GNSSchipset 1404 solely comprises the components of a GNSS receiver such asdescribed above with reference to FIG. 12. Due to the increasing use oflocation-services applications, GNSS chipsets are in widespread use invirtually every type of handheld device being manufactured including,but not limited to cellular telephones, digital cameras, etc. As aresult, the cost, size, and weight of GNSS chipsets has dropped. As anexample, a cellular telephone GNSS chipset can have a footprint as smallas 25 mm². Thus, integrating a GNSS chipset into receiving component1402 does not incur a significant penalty in terms of size or weight. Inanother embodiment, GNSS chipset 1404 comprises a complete integratedcircuit component as in use in cellular telephones including integratedcircuits for GNSS signal processing, cellular communications,processor(s), and other short-range wireless communication links as willbe discussed in greater detail below.

The GNSS chipset normally processes the GNSS signals from space todetermine a number of signal observables, referred to a raw GNSSobservables, which include pseudoranges for up to 12 satellites that maybe in view, Doppler shift information for each satellite signal, orsignals in the case of dual frequency L1 and L2 tracking, and carrierphase information for each signal being tracked. These observables maybe processed locally in the chipset via stored program algorithms, or inan embodiment, transferred from the chipset to a nearby cellular phonefor enhanced processing via the services available in the cellphone.

Wireless communication component 1405 comprises a wireless radiotransmitter, or transceiver configured to transmit GNSS data including,but not limited to, raw GNSS observables from GNSS chipset 1404 tocellular device 1410. In accordance with various embodiments, wirelesscommunication component 1405 may operate on/in compliance with anysuitable wireless communication protocol including, but not limited to:mesh networking, implementations of the IEEE 802.15.4 specification forpersonal area networks, and implementations of the Bluetooth® standard.Personal area networks refer to short-range, and often low-data-rate,wireless communications networks. In accordance with embodiments of thepresent technology, components of a wireless personal area network areconfigured for automatic detection of other components and forautomatically establishing wireless communications. In anotherembodiment, receiving component 1402 may also include another wirelesscommunication component (not shown) which is capable of communicatingacross longer distances. This second wireless communication component ofreceiving component 1402, when included, may operate on any suitablewireless communication protocol including, but not limited to: Wi-Fi,WiMAX, WWAN, implementations of the IEEE 802.11 specification, cellular,two-way radio, and satellite-based cellular (e.g., via the Inmarsat orIridium communication networks). The discussion above and the depictionin FIG. 14 indicates that all of the sub-components of receivingcomponent 1402 are disposed proximate to each other, or within a singleunit; however, in various embodiments, the components of receivingcomponent 1402 can be distributed, but are not components of cellulardevice 1410 itself.

It is noted that in accordance with various embodiments, GNSS chipset1404 and wireless communication component 1405 are integrated ascomponents of a larger chipset such as a cellular telephone chipsethaving cellular communication, GNSS, processing, and Bluetooth®/wirelesspersonal area network capabilities integrated into a single product.Additionally, various embodiments can utilize GNSS chipsets of varyingquality as GNSS chipset 1404. For example, there is a wide range ofcapabilities and prices of GNSS chipsets on the market today rangingfrom a few dollars to a hundred dollars or more depending in part uponwhat features are supported by the chipset. Cellular device GNSSchipsets are typically configured to deliver an “abbreviated featureset.” In an embodiment, GNSS chipset 1404 may be configured and accessedto obtain raw GNSS observables data by other devices within the network,in manners described herein, for further processing. This additional,further processing is due to processing limitations of the chipset.Thus, while it may be possible for receiving component 1402 to deriveits own position in one or more embodiments, or be capable of moreadvanced operations, it instead is used to derive data such as rawpseudorange information and carrier phase information which is thenwirelessly transmitted to cellular device 1410 for further processing.In at least one embodiment, receiving component 1402 also wirelesslytransmits other data to cellular device 1410 such as, but not limitedto, Doppler frequency shift data. In FIG. 14, receiving component 1402further comprises a battery 1406, a power line conditioner 1407, and apower connection 1408. Battery 1406 is for providing power to receivingcomponent 1402. Power line conditioner 1407 is for converting and/orconditioning power received via power connection 1408 to a propervoltage and/or characteristics suitable for re-charging battery 1406, orfor directly powering receiving component 1402. In accordance withvarious embodiments, circularly polarized GNSS antenna 1403, GNSSchipset 1404, wireless communication component 1405, battery 1406, powerline conditioner 1407, and power connection 1408 are disposed within ahousing 1409. In accordance with one or more embodiments, powerconnection 1408 comprises a power socket configured to receive a powerplug. In accordance with at least one embodiment, power connection 1408comprises a wireless power connection such as, for example, an inductivepower charger, or a capacitive power charger. In accordance with variousembodiments, power line conditioner 1407 may be an optional component inthe event that the power connection is configured to provide voltage inaccordance with the requirements of receiving component 1402.

In accordance with various embodiments, cellular device 1410 comprises acellular telephone, a dedicated GNSS data collector, or another portableelectronic device configured to communicate via a cellular network. Forexample, cellular device 1410 can be implemented as cellular device 100of FIG. 1A, SOCS 190 of FIG. 1D, cellular device 200 of FIG. 2, etc.Furthermore, it is noted that all of the functionality described abovewith reference to improved accuracy SUPL client 101, as well as allcomponents thereof, and operating system 160 and its sub-components areoperable upon cellular device 1410. In FIG. 14, cellular device 1410comprises second wireless communication component 1411, processor 1412,and cellular communication component 1413. In various embodiments,second wireless communication component 1411 is configured to wirelesslycommunicate with wireless communication component 1405 of receivingcomponent 1402. Thus, second wireless communication component 1411 mayalso operate on/in compliance with any suitable wireless communicationprotocol including, but not limited to: mesh networking, implementationsof the IEEE 802.15.4 specification for personal area networks, andimplementations of the Bluetooth® standard as appropriate to communicatewith wireless communication component 1405. Processor 1412 is configuredto process data conveyed from receiving component 1402 via secondwireless communication component 1411 to determine the location of GNSSantenna 1403. It is noted that processor 1412 is analogous withprocessor 109 described above with reference to FIGS. 1A, 1D, and FIG.2. Cellular communication component 1413 may operate on any suitablewireless communication protocol including, but not limited to: Wi-Fi,WiMAX, WWAN, implementations of the IEEE 802.11 specification, cellular,two-way radio, FM radio, and satellite-based cellular (e.g., via theInmarsat or Iridium communication networks) and is operable forreceiving pseudorange correction data from various sources including,but not limited to, WAAS pseudorange corrections, DGPS pseudorangecorrections, and PPP pseudorange corrections.

In operation, GNSS antenna 1403 receives GNSS signals from GNSSsatellites in view. As will discussed in greater detail below, due toits disposition apart from cellular device 1410, receiving component1402 is better located to receive GNSS signals than may be the caseusing a cellular telephone, or other portable electronic device, alone.As stated above, in at least one embodiment, GNSS chipset 1404 comprisesa GNSS chipset operable for processing the respective GNSS signalsreceived by GNSS antenna 1403. In one embodiment, GNSS chipset 1404provides one or more of pseudorange information, Doppler shiftinformation, and real carrier phase information to wirelesscommunication component 1405 which in turn forwards that data tocellular device 1410 via second wireless communication component 1411.In one embodiment, this can be performed automatically and thisautomatic forwarding of data from receiving component 1402 can beinitiated when a cellular device 1410 is detected in the vicinity. Thiscan further comprise a login/handshake procedure. In another embodiment,chipset accessor logic 141 is configured to access the GNSS chipsetcomprising GNSS chipset 1404. Thus, chipset accessor logic 141 willgenerate a message which initiates the sending of pseudorange data fromreceiving component 1402. Furthermore, accessing logic 1110-B caninitiate accessing carrier phase data from receiving component 1402. Inresponse to requests for this data, GNSS chipset 1404 can process thesignals from the GNSS satellites in view and send the pseudorange andcarrier phase data to cellular device 1410 via wireless communicationcomponent 1405. Processor 1412 of cellular device 1410 can then use thisdata to derive the position of GNSS antenna 1403. Additionally, usingpseudorange corrections received via cellular communication component1413, cellular device 1410 can further refine the processing of receivedGNSS signals as described above.

Unless otherwise specified, one or more of the various embodimentsdescribed herein can be implemented as hardware, such as circuitry,firmware, or computer readable instructions that are stored onnon-transitory computer readable storage medium. The computer readableinstructions of the various embodiments described herein can be executedby a hardware processor, such as central processing unit, to cause thecellular device 100, 200 to implement the functionality of variousembodiments. For example, according to one embodiment, the SUPL client101 and the operations of the flowcharts 400-1100 depicted in FIGS. 4-11are implemented with computer readable instructions that are stored oncomputer readable storage medium, which can be tangible ornon-transitory or a combination thereof, and can be executed by ahardware processor 109 of a cellular device 100, 200, receivingcomponent 1402, and cellular device 1410.

FIGS. 15A-15M show various uses of receiving component 1402 inaccordance with various embodiments. In FIG. 15A, receiving component1402 is disposed on top of a support pole 1501. Professional-gradecomplete GNSS receiver systems are also disposed on the top of suchpoles, and the assembly is referred to as a “rover” position determiningsystem. Devices similar to support pole 1501 are commonly used insurveying as a sighting target for a transit in order to determine theposition at which the point of the pole is located on the ground. Thesetarget poles may also be equipped with receiving component 1402. Inaccordance with various embodiments, support pole 1501 is outfitted witha receiving component 1402. As described above, receiving component 1402is used to receive GNSS satellite signals and to output to cellulardevice data used by cellular device 1410 to determine the position ofreceiving component 1402. As shown in FIG. 15A, a user is carryingcellular device 1410 in a pocket and communicates with receivingcomponent 1402 via a short-range wireless communication link such asBluetooth. In accordance with various embodiments, receiving component1402 can be removably coupled with support pole 1501. For example,receiving component 1402 can be coupled with support pole 1501 usingmechanical fasteners, hook and loop (e.g., Velcro®), snapped into areceptacle/compartment of support pole 1501, etc. It is noted that othercomponents can comprise support pole 1501 as well including, but notlimited to, reflectors, prisms, data input components, display devices,solar panels, etc. In use, an operator would place tip 1502 of supportpole 1501 at a location in order to determine the position of thatlocation. Receiving component 1402 receives signals from orbiting GNSSsatellites and outputs, via a short-range wireless link, pseudorange andcarrier phase information based upon each of the GNSS satellite signalsreceived. Cellular device 1410 uses the pseudorange and carrier phaseinformation, as well as GNSS correction data received via, for example,a cellular telephone network (e.g., 222 of FIG. 2) to determine theposition of circularly polarized GNSS antenna 1403 of receivingcomponent 1402. It is noted that there will be a height differencebetween circularly polarized GNSS antenna 1403 and tip 1502. Inaccordance with various embodiments, this height difference can beaccounted for automatically by operating system 160, location managerlogic 161, or the like. In accordance with various embodiments,receiving component 1402 can be coupled with support pole 1501 for thepurpose of surveying a location (e.g., in conjunction with cellulardevice 1410), detached, and used for another purpose as described ingreater detail below.

FIG. 15B shows a portable traffic management device (e.g., traffic cone1505) having a receiving component 1402 disposed on top. In accordancewith various embodiments, receiving component 1402 can be coupled withvarious devices as described above. In the embodiment of FIG. 15Breceiving components 1402 can be coupled with respective traffic cones1505 and placed at a location to make an ad-hoc barrier. For example, ifa site has a location which may be considered off-limits to traffic dueto safety or environmental concerns, traffic cones 1505 can be used toprovide a visual delineation of that off-limits area. Additionally,because each traffic cone 1505 is coupled with a receiving component1402, the position of each of those cones can be determined and reportedto another entity such as a site management server, or geo-fencingserver. For example, when each traffic cone 1505 is emplaced, it willcommunicate its pseudorange and carrier phase information wirelesslywith cellular device 1410 of an operator (e.g., see FIG. 15A). Inaccordance with various embodiments, cellular device 1410 will recordand store the location of each of traffic cones 1505 and/orautomatically forward these locations to a central server. It is notedthat other types of traffic barriers can be fitted with receivingcomponent 1402 such as pre-cast concrete traffic barriers, A-frametraffic barriers, fences, barrels, gates, water/sand filled barriers,etc. However, these barriers can be quickly emplaced and their positiondetermined and mapped without extra steps to determine their position.Also, because receiving component 1402 does not provide full positiondetermining functionality, but rather exports pseudoranges, carrierphases, and other information to cellular device 1410 for processing,they are much less attractive to thieves who cannot use or sellreceiving component 1402 as readily as a fully functioning GNSSreceiver. In accordance with various embodiments, receiving component1402 can be permanently coupled with traffic cone 1505, or attached inan ad-hoc manner when emplaced. It is noted that although not shown inFIG. 15B, traffic cone 1505 can comprise a solar panel to generateelectricity and connector for providing electrical power from the solarpanel to receiving component 1402.

Wearable GNSS Receiver Component and Cellular Device

FIG. 15C shows a wearable article of clothing comprising GNSSpositioning system 1400 in accordance with various embodiments. In FIG.15C, this wearable GNSS system takes the form of vest 1510, whichcomprises a compartment or pocket 1511 on a shoulder (the left shoulderin this embodiment) which is configured to hold receiving component1402. A second pocket 1512 of vest 1510 is configured to hold cellulardevice 1410. As shown in FIG. 15C, the disposition of receivingcomponent 1402 places it in a better position for receiving GNSSsatellite signals than cellular device 1410, either in pocket 1512 orwhen held in a user's hand. Furthermore, as described above, receivingcomponent 1402 utilizes an antenna design which is optimized for GNSSsatellite signal reception in comparison with the antenna designstypically found in cellular devices. As a result, a user wearing vest1510 will realize greater precision in determining his position usingGNSS positioning system 1400, particularly when carrier phase smoothinglogic 152 is implemented in cellular device 1410. Also shown in FIG. 15Cis a solar panel 1513 which generates electricity. Implementations ofvest 1510 comprise solar panels 1513 at various locations to facilitateproviding electrical power to receiving component 1402 via a powercoupling (not shown) which plugs into power connection 1408. Typically,solar panels are known for being linear and rigid and thereforedifficult to integrate into application where a curved and/or flexiblesurface is provided. However, there are thin solar cells which areflexible in at least one dimension which can be used in accordance withvarious embodiments. One example is a commercially available thin filmof gallium arsenide manufactured by Alta Devices of Sunnyvale, Calif. Inanother embodiment, a process for embedding solar panels withininfusion-molded composite parts can be used. In accordance with at leastone embodiment, one or more rigid solar cells can be combined into asolar panel by, for example, attaching them to a substrate or gusset.The plurality of rigid solar cells can be attached so that they comprisea curved surface in various embodiments. This substrate or gusset can beattached to the wearable article of clothing by sewing it on, adhesive,mechanical fasteners, hook and loop (e.g., Velcro®), or the like. It isnoted that additional solar panels can be integrated into vest 1510, andat other locations, but were omitted for the purpose of clarity.Furthermore, vest 1510 can include reflective panels and other safetyfeatures typically integrated into safety vest designs. It is noted thatwhile the present description of vest 1510 is directed to safety vestsworn by construction personnel, various embodiments can be implementedas military body armor, load bearing equipment, lifejackets, or regulararticles of clothing such as hiking jackets, rain jackets, etc.Furthermore, while FIG. 15C shows a dedicated pocket 1511 configured forholding receiving component 1402, in another embodiment receivingcomponent 1402 is simply worn on the outside of an article of clothingand attached using, for example, hook and loop (e.g., Velcro®) strips,pins, clips, etc. In one embodiment, pocket 1511 itself is detachablefrom vest 1510, or other articles of clothing and is attached asdescribed above.

Helmet-Mounted GNSS Receiver Positioning System

FIGS. 15D and 15E show a construction hard hat 1515 having a pocket 1516which is configured for holding receiving component 1402. Hard hat 1515is presented as one embodiment of a helmet (e.g., hardened safetyheadwear), others would include, without limitation, sports helmets(e.g., football helmets, bicycle helmets, equestrian helmets, motorcyclehelmets and the like), military helmets, police helmets, firefighter'shelmets, bump caps and the like. In FIGS. 15D and 15E, pocket 1516 isshown with a strap which prevents receiving component 1402 from fallingout. It is recognized that other configurations for securing receivingcomponent within pocket 1516 are envisioned in various embodiments. Inone embodiment, pocket 1516 is a molded-in component of hard hat 1515.Alternatively, pocket 1516 can be attached directly to hard hat 1515using, for example, hook and loop (e.g., Velcro®) strips, adhesives,mechanical fasteners, brackets, etc. In FIG. 15E, hard hat 1515 furthercomprises at least one solar panel 1517 for providing power to receivingcomponent 1402 as described above via electrical connection 1518. Asdescribed above, the embodiments shown in FIGS. 15D and 15E positionreceiving component 1402 higher up and thus in a position for improvedreception compared with handheld components, particularly cellulardevices, which typically experience interference from the user's bodyand poor reception due to the GNSS antenna design typically used incellular devices. Also, while shown disposed at the top of hard hat1515, receiving component 1402 can be disposed at any location of hardhat 1515. Furthermore, while shown as a separate unit for clarity, thecomponents of receiving component 1402 can be integrated into hard hat1401 itself in one or more embodiments. As described above, inaccordance with at least one embodiment, receiving component 1402 isconfigured to utilize a quadrifiler helix antenna 1519 as shown in FIG.15E.

FIG. 15F shows another embodiment of a wearable article of clothingcomprising GNSS positioning system 1400 in accordance with variousembodiments. In FIG. 15F, the wearable article of clothing againcomprises a construction hard hat 1520 comprising at least one solarpanel 1517, as described above, to generate electricity. Additionally,hard hat 1520 comprises a removable cover 1521 to a compartment 1522 inthe top of hard hat 1520 into which receiving component 1402 can beplaced. In accordance with various embodiments, receiving component 1402can be snapped into compartment 1522 and cover 1521 emplaced to presenta less cluttered appearance. Additionally, cover 1521 is configured toprotect receiving component from dust, moisture, and impact when it isin place over compartment 1522. In various embodiments, cover 1521comprises a material which is transparent to GNSS satellite radiosignals. In an embodiment, receiving component 1402 may comprise aself-contained power supply system consisting of a battery. In anembodiment, the battery may be rechargeable, and solar panel(s) 1517 onthe hard hat may supply the electrical power via connection from thesolar panel(s) 1517 located on the outer surface of hard hat 1520. In atleast one embodiment, when receiving component 1402 is placed intocompartment 1522, power connection 1408 is engaged with correspondingpower connections within compartment 1522 such that receiving component1402 can receive electrical power from solar panel 1517. In accordancewith various embodiments, cover 1521 can be snapped into place and/orutilize mechanical fasteners to secure it in place. It is noted thatcover 1521 can be hinged such that it cannot be entirely detached fromhard hat 1520 in at least one embodiment.

FIG. 15G shows another embodiment of a construction hard hat 1525 havinga cover 1526 to a compartment 1527 into which receiving component 1402can be placed. In the embodiment of FIG. 15G, compartment 1527 isdisposed on the underside of hard hat 1525. This provides greaterprotection from moisture that the embodiment shown in FIG. 15F in whichcompartment 1522 is accessible from above. As with hard hat 1520 of FIG.15F, in at least one embodiment, hard hat 1525 can be made of a materialwhich is transparent to GNSS satellite radio signals. Additionally,compartment 1527 can be disposed such that when receiving component 1402is placed within it, power connection 1408 is engaged with correspondingpower connections of hard hat 1525 such that receiving component 1402receives electrical power from solar panel 1517. In accordance withvarious embodiments, cover 1526 can be snapped into place and/or utilizemechanical fasteners to secure it in place. It is noted that cover 1526can be hinged such that it cannot be entirely detached from hard hat1525 in at least one embodiment. Additionally, cover 1526 is configuredto protect receiving component 1402 from dust, moisture, and impact whenit is in place beneath compartment 1527.

FIGS. 15H and 15I are cross section views of hard hats 1520 and 1525respectively in accordance with various embodiments. In FIG. 15H, cover1521 is shown removed from compartment 1522 with receiving component1402 disposed therein. Also shown in FIG. 15H is solar panel 1517 togenerate electricity. Solar panel 1517 is coupled with and provideselectrical power to receiving component 1402 via electrical connection1523. Similarly, FIG. 15I shows cover 1526 removed from compartment 1527with receiving component 1402 disposed within. Again, receivingcomponent 1402 is shown coupled with solar panel 1517 which provideselectrical power to receiving component 1402 via electrical connection1528.

FIGS. 15J and 15K are top and side views respectively of a removableassembly 1530 in accordance with various embodiments. In FIGS. 15J and15K, removable assembly 1530 comprises a base 1531 onto which receivingcomponent 1402 is coupled. It is noted that in accordance with at leastone embodiment, receiving component 1402 is removably coupled with base1531 and can be removed and used in other configuration such as shown inFIGS. 15A-15J. In FIGS. 15J and 15K, removable assembly 1530 furthercomprises metallic fingers 1532 which couple base 1531 with hard hat1535. In accordance with various embodiments, metallic or plasticfingers 1532 comprise a flexible material designed to conform to theshape of hard hat 1535. In accordance with various embodiments,removable assembly 1530 is designed to snap in place around hard hat1535. In an embodiment, the metallic or plastic fingers 1532 are coveredwith solar cells (not shown), to provide power for receiving component1402. In an embodiment, an adhesive may be applied to base 1531 to keepremovable assembly 1530 in place. In various embodiments, removableassembly 1530 can be snapped into position by applying or pushing itdown over the top of hard hat 1535. In various embodiments, metallic orplastic fingers 1532 are coupled with a substrate 1533 such as a webbingwhich is shown in FIGS. 15J and 15K. It is noted that variousconfigurations of a substrate 1533 can be implemented in accordance withvarious embodiments. For example, substrate 1533 may comprise an elasticmaterial which pulls metallic or plastic fingers 1532 into closercontact with hard hat 1535 when removable assembly 1530 is in place.Furthermore, the points at which substrate 1533 come into contact withhard hat 1535 may provide additional friction to keep removable assembly1530 from sliding around on top of hard hat 1535. It is noted that theorientation of receiving component 1402 shown in FIGS. 15J-15M is wellsuited for the utilization of a GNSS patch antenna (e.g., 1403) asdescribed above.

FIGS. 15L and 15M are top and side views respectively of removableassembly 1530 in accordance with various embodiments. It is noted thatthe configuration of removable assembly 1530 shown in FIGS. 15J-15M isfor the purpose of illustration and that other configurations can beimplemented in accordance with various embodiments.

In accordance with various embodiments, the receiving component 1402shown in FIGS. 15D-15M receives GNSS satellite radio signals and derivesrespective carrier phase and pseudorange information derived from eachGNSS satellite radio signal it receives. It is noted that additionalGNSS information such as Doppler shift information can also be derivedby receiving component 1402. Receiving component 1402 then wirelesslytransmits the carrier phase and pseudorange information to a cellulardevice 1410. Typically, the cellular device 1410 is carried by the userwearing hard hat 1515, 1520, 1525, and/or 1535. Then, the primaryprocessor (e.g., processor 1412 of FIG. 14) derives the position ofreceiving component 1402 using the respective pseudorange and carrierphase information, as well as any GNSS corrections received from acorrections source. Typically, the GNSS corrections received by cellulardevice 1410 are received via a cellular network 222 and/or local Wi-Fi224. It is noted that processor 1412 comprises the primary processor ofcellular device 1410 rather than a dedicated GNSS processor. Thus,various embodiments are able to leverage the greater processing powerthat is being integrated into cellular devices to improve theperformance in determining the position of receiving component 1420, ormore specifically, circularly polarized GNSS antenna 1403.

FIGS. 16A-16D are a block diagrams of components of receiving components1402 in accordance with various embodiments. In the embodiment of FIG.16A, rather than implementing an entire GNSS chipset 1404 (e.g., acellular telephone GNSS chipset, or a dedicated GNSS data collectorchipset), receiving component 1402 comprises a partial GNSS chipset1404A with the other components of a partial GNSS chipset 1404B residentupon cellular device 200 which is shown in FIG. 17. It should be notedthat in FIG. 17, cellular device 1410 is an embodiment of cellulardevice 200 (e.g., cellular device 200 of FIG. 2) comprising thecomponents shown in FIG. 2 with the addition of the partial GNSS chipset1404B. The following discussion will refer to both FIGS. 16A-D and 17 tomore clearly explain the operation of this embodiment. In FIG. 16A,received L1 and L2 signals are generated by at least one GPS satellite.Each GPS satellite generates different signal L1 and L2 signals and theyare processed by different digital channel processors 1652 which operatein the same way as one another. In accordance with various embodiments,circularly polarized GNSS antenna 1403 receives respective signals froma plurality of GNSS satellites.

If both L1 and L2 signals are to be processed, the antenna must becapable of receiving both frequencies. This has been found to beextremely difficult if not impossible, because of the separationfrequency between L1 and L2 and the narrow bandwidths of patch antennas.Therefore, most dual frequency systems employ two patch antennas, onemounted atop the other, as is found in the professional grade GNSSpositioning systems. Other physical configurations are possible, such asmounting the two patch antennas side by side. A new L2 frequency willbecome available in the future, known as L2C GNSS signal and which canbe used in accordance with various embodiments. It will enable directreception via the same kind of code acquisition and processing as is nowused on L1. For many applications, a single frequency L1 receiverprovides adequate position fix accuracy, especially when the variouscorrections systems recited in previous portions of this application areutilized.

FIG. 16A shows GPS signals (L1=1575.42 MHz, L2/L2C=1227.60 MHz) enteringreceiving component 1402 through a dual frequency antenna 1403. Masteroscillator 1648 provides the reference oscillator which drives all otherclocks in the system. Frequency synthesizer 1638 takes the output ofmaster oscillator 1648 and generates important clock and localoscillator frequencies used throughout the system. For example, in oneembodiment frequency synthesizer 1638 generates several timing signalssuch as a 1st (local oscillator) signal LO1 at 1400 MHz, a 2nd localoscillator signal LO2 at 175 MHz, an SCLK (sampling clock) signal at 25MHz, and a MSEC (millisecond) signal used by the system as a measurementof local reference time.

A filter/LNA (Low Noise Amplifier) 1634 performs filtering and low noiseamplification of both L1 and L2 signals. In some embodiments, thedownconvertor 1636 mixes both L1 and L2 signals in frequency down toapproximately 175 MHz and outputs the analog L1 and L2 signals into anIF (intermediate frequency) processor 1650. In other embodiments, suchas those shown in FIG. 16B and FIG. 16D where no L2 component isutilized by the partial GNSS receiver, downconvertor 1636 may only mixand output the analog L1 signal to the IF processor 1650. IF processor1650 takes the analog L1 and/or L2 signals at approximately 175 MHz andconverts them into digitally sampled L1 and L2 inphase (L1 I and L2 I)and quadrature signals (L1 Q and L2 Q) at carrier frequencies 420 KHzfor L1 and at 2.6 MHz for L2 signals respectively.

At least one digital channel processor 1652 inputs the digitally sampledL1 and L2 inphase and quadrature signals. All digital channel processors1652 are typically are identical by design and typically operate onidentical input samples. Each digital channel processor 1652 is designedto digitally track the L1 and L2 signals produced by one satellite bytracking code and carrier signals from code and carrier phasemeasurements in conjunction with the GNSS microprocessor system 1654.One digital channel processor 1652 is capable of tracking one satellitein both L1 and L2 channels. GNSS microprocessor system 1654 facilitatestracking and measurements processes, providing pseudorange and carrierphase measurements for a determining position fix logic (e.g.,navigation processor 1758). In one embodiment, microprocessor system1654 provides signals (e.g., 1670) to control the operation of one ormore digital channel processors 1652.

In the embodiment shown in FIG. 16B, the components of partial GNSSchipset 1404A discussed above are the same with the exception that IFprocessor 1650 outputs an L1 signal only. In another embodiment, shownin FIG. 16C, IF processor 1650 outputs an L1 signal and an L2C signalonly. The L2C GNSS signal is a new GNSS signal being phased in whichpermits ionospheric correction, faster signal acquisition, and enhancedreliability. Alternatively, as shown in FIG. 16D, in one embodiment, IFprocessor 1650 outputs and L1I and L1Q signal only. Many receivers donot provide L1Q, as L1I may be adequate for most applications that donot require professional grade high precision.

According to one embodiment, the microprocessor system 1750 receives thepseudorange information 1672, Doppler Shift information 1674, and realCarrier Phase Information 1676 from second wireless communicationcomponent 1411 and provides them to the determining position fix logic(e.g., navigation processor 1758 and/or processes running thereon).Determining position fix logic performs the higher level function ofcombining measurements in such a way as to produce position, velocityand time information for the differential and surveying functions, forexample, in the form of a position fix 1780. Storage 1760 is coupledwith determining position fix logic and microprocessor system 1750. Itis appreciated that storage 1760 may comprise a volatile or non-volatilestorage such as a RAM or ROM, or some other computer readable memorydevice or media. In some embodiments, determining position fix logicperforms one or more of the methods of position correction describedherein.

In some embodiments, microprocessor system 1750 and/or determiningposition fix logic receive additional inputs for use in receivingcorrections information via cellular communication component 1413.According to one embodiment, an example of the corrections informationis WAAS corrections. According to one embodiment, examples ofcorrections information are differential GPS corrections, RTKcorrections, signals used by the previously referenced Enge-Talbotmethod, wide area augmentation system (WAAS) corrections, and PPPcorrections among others

FIG. 18 is a flowchart of a method 1800 of extracting pseudorangeinformation using a cellular device in accordance with variousembodiments. In operation 1810, a Global Navigation Satellite System(GNSS) chipset is accessed which is physically remote from a cellulardevice, wherein the GNSS chipset provides raw GNSS observablesinformation based upon signals received from a circularly polarized GNSSantenna. As described above, in various embodiments receiving component1402 of FIG. 14 comprises a circularly polarized GNSS antenna (e.g.,patch antenna 1403 of FIG. 14, or quadrifiler helix antenna 1519 of FIG.15E), a GNSS chipset 1404 and a wireless communication component 1405disposed within a housing 1409. As described above, in variousembodiments, the GNSS chipset (e.g., GNSS chipset 1404 of FIG. 14)comprises an abbreviated feature set GNSS chipset. In accordance withvarious embodiments, the GNSS chipset (e.g., GNSS chipset 1404 of FIG.14) is configured to process at least one of an L1C GNSS signal and anL2C GNSS signal. In accordance with various embodiments, the GNSS rawobservables information comprises at least one of pseudorangeinformation, carrier phase information, and/or Doppler shiftinformation.

In operation 1820, the raw GNSS observables information is wirelesslytransmitted from the GNSS chipset to the cellular device. As describedabove, in various embodiments wireless communication component 1405 isused to wirelessly transmit respective pseudorange informationrespective carrier phase information derived from each of the GNSSsatellite radio signals received via circularly polarized GNSS antenna1403 to a cellular device (e.g., 1410 of FIG. 14) which is separate fromreceiving component 1402. As described above, receiving component 1402can be coupled with various articles of clothing, helmets, support polesfor surveying operations, moveable traffic management devices andbarriers, etc.

In operation 1830, the raw GNSS observables information is extracted bya processor of the cellular device. As described above, processor 1412is utilized as the primary processor of cellular device 1410.

In operation 1840, the raw GNSS observables information is used by theprocessor, in addition to GNSS corrections from at least one correctionsource, to determine a position of the circularly polarized GNSSantenna. As described above, in accordance with various embodiments adetermination is made whether to apply any improvements, includingimprovements to the pseudorange information, using position accuracyimprovement determination logic (e.g., 180B of FIG. 1B) resident uponcellular device 1410. If it is determined that improvements are to beapplied by position accuracy improvement determination logic 180B, candetermine one or more improvements from a variety of GNSS correctionssources including real carrier phase information, reconstructed carrierphase information, WAAS, DGPS, PPP, RTX, RTK and VRS corrections. Inaccordance with various embodiments, the pseudorange informationreceived by cellular device 1410 is smoothed to create smoothedpseudorange information using smoothing logic (e.g., 152 of FIG. 1B)resident upon cellular device 1410. In accordance with variousembodiments, this smoothing can be based upon real carrier phaseinformation that is derived based on the carrier phase informationreceived from receiving component 1402 using real carrier phase logic(e.g., 152A of FIG. 1B) resident upon cellular device 1410. Inaccordance with various embodiments the smoothed pseudorange informationis corrected using correcting logic (e.g., 15I of FIG. 1B) resident uponcellular device 1410 to create corrected pseudoranges. In accordancewith various embodiments, the GNSS corrections are not contained in aGNSS signal, but are received via, for example, cellular network 222and/or local Wi-Fi 224 of FIG. 2. In accordance with variousembodiments, accessing logic of cellular device 1410 (e.g., 110B of FIG.1B) is used to access Wide Area Augmentation System (WAAS) pseudorangecorrections. The WAAS pseudorange corrections are stored in a memorydevice (e.g., 210 of FIG. 2). The smoothed pseudorange informationdescribed above is accessed as well as the WAAS pseudorange correctionsusing pseudorange information processing logic (e.g., 150 of FIG. 1A) ofcellular device 1410. Cellular device 1410 then determines a positionfix of circularly polarized GNSS antenna 1403 using pseudorangeinformation processing logic 150 based on the smoothed pseudorangeinformation and the WAAS pseudorange corrections using processor 1412 ofcellular device 1410. In accordance with various embodiments, correctedpseudoranges can be created based on one or more types of pseudorangecorrections received by cellular device 1410, selected from a groupconsisting of Differential Global Positioning System (DGPS), PrecisePoint Positioning (PPP), Real Time Kinematic (RTK), and RTX corrections.

CONCLUSION

Example embodiments of the subject matter are thus described. Althoughthe subject matter has been described in a language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

Various embodiments have been described in various combinations andillustrations. However, any two or more embodiments or features may becombined. Further, any embodiment or feature may be used separately fromany other embodiment or feature. Phrases, such as “an embodiment,” “oneembodiment,” among others, used herein, are not necessarily referring tothe same embodiment. Features, structures, or characteristics of anyembodiment may be combined in any suitable manner with one or more otherfeatures, structures, or characteristics.

What is claimed is:
 1. A method of extracting pseudorange informationusing a cellular device, the method comprising: accessing a GlobalNavigation Satellite System (GNSS) chipset which is physically remotefrom a cellular device, wherein said GNSS chipset provides raw GNSSobservables information based upon signals received from a circularlypolarized GNSS antenna; wirelessly transmitting the raw GNSS observablesinformation from said GNSS chipset to said cellular device; extractingthe raw GNSS observables information by a processor of said cellulardevice; and using, by said processor, the raw GNSS observablesinformation, in addition to GNSS corrections from at least onecorrection source, to determine a position of said circularly polarizedGNSS antenna.
 2. The method of claim 1 wherein said processor isutilized as a primary processor of said cellular device.
 3. The methodof claim 1 wherein said raw GNSS observables information comprisescarrier phase information.
 4. The method of claim 1 wherein said rawGNSS observables information comprises Doppler shift information.
 5. Themethod of claim 1 wherein said raw GNSS observables informationcomprises pseudorange information.
 6. The method of claim 5 furthercomprising: smoothing the pseudorange information to create smoothedpseudorange information using smoothing logic of said receivingcomponent.
 7. The method of claim 6 further comprising: smoothing thepseudorange information based on real carrier phase information that isderived based on the carrier phase information using real carrier phaselogic of said cellular device.
 8. The method of claim 6 furthercomprising: correcting said smoothed pseudorange information to createcorrected pseudoranges using correcting logic of said cellular device.9. The method of claim 8 further comprising: creating the correctedpseudoranges based on one or more types of pseudorange correctionsreceived by said cellular device, said pseudorange corrections selectedfrom a group consisting of Differential Global Positioning System(DGPS), Precise Point Positioning (PPP), Real Time Kinematic (RTK), andRTX.
 10. The method of claim 6 further comprising: accessing Wide AreaAugmentation System (WAAS) pseudorange corrections using accessing logicof said cellular device; storing the WAAS pseudorange corrections in amemory device of said cellular device; accessing the smoothedpseudorange information and the WAAS pseudorange corrections usingpseudorange information processing logic of said cellular device; anddetermining a position fix of said circularly polarized GNSS antennausing the pseudorange information processing logic based on the smoothedpseudorange information and the WAAS pseudorange corrections using saidprocessor.
 11. The method of claim 5 further comprising: determiningwhether to apply any improvements to the pseudorange information usingposition accuracy improvement determination logic of said cellulardevice; and determining one or more improvements to be applied to thepseudorange information, if the determination is that any improvementswill be applied using the position accuracy improvement determinationlogic of said cellular device.
 12. The method of claim 1 furthercomprising: disposing said GNSS chipset, said circularly polarized GNSSantenna, and a wireless communication component in a housing of areceiving component which is separate from said cellular device.
 13. Themethod of claim 12 further comprising: coupling said receiving componentwith an article of clothing.
 14. The method of claim 13 wherein saidarticle of clothing comprises a solar panel configured to generateelectricity, said method further comprising: using said solar panel torecharge a battery disposed within said receiving component.
 15. Themethod of claim 12 further comprising: disposing said receivingcomponent with a support pole used to locate a point on the ground. 16.The method of claim 12 further comprising: disposing said receivingcomponent upon a moveable traffic management device.
 17. The method ofclaim 1 wherein said GNSS chipset comprises an abbreviated feature setGNSS chipset.
 18. The method of claim 1 wherein said GNSS chipset isconfigured to process at least one of an L1 GNSS signal and an L2C GNSSsignal.
 19. The method of claim 1 wherein the GNSS corrections from saidat least one correction source are not contained in a GNSS signal.
 20. Anon-transitory computer readable storage medium having computer readableinstructions stored thereon for causing a computer system to perform amethod of extracting pseudorange information using a cellular device,the method comprising: accessing a Global Navigation Satellite System(GNSS) chipset which is physically remote from a cellular device,wherein said GNSS chipset provides raw GNSS observables information uponsignals received from a circularly polarized GNSS antenna; wirelesslytransmitting the raw GNSS observables information from said GNSS chipsetto said cellular device; extracting the raw GNSS observables informationby a processor of said cellular device; and using by said processor, theraw GNSS observables information, in addition to GNSS corrections fromat least one correction source, to determine a position of saidcircularly polarized GNSS antenna.
 21. The non-transitory computerreadable storage medium of claim 20 wherein said processor is utilizedas a primary processor of said cellular device.
 22. The non-transitorycomputer readable storage medium of claim 20 wherein said raw GNSSobservables information comprises carrier phase information.
 23. Thenon-transitory computer readable storage medium of claim 20 wherein saidraw GNSS observables information comprises Doppler shift information.24. The non-transitory computer readable storage medium of claim 20wherein said raw GNSS observables information comprises pseudorangeinformation.
 25. The non-transitory computer readable storage medium ofclaim 24 wherein said method further comprises: smoothing thepseudorange information to create smoothed pseudorange information usingsmoothing logic of said receiving component.
 26. The non-transitorycomputer readable storage medium of claim 25 wherein said method furthercomprises: smoothing the pseudorange information based on real carrierphase information that is derived based on the carrier phase informationusing real carrier phase logic of said cellular device.
 27. Thenon-transitory computer readable storage medium of claim 25 wherein saidmethod further comprises: correcting said smoothed pseudorangeinformation to create corrected pseudoranges using correcting logic ofsaid cellular device.
 28. The non-transitory computer readable storagemedium of claim 27 wherein said method further comprises: creating thecorrected pseudoranges based on one or more types of pseudorangecorrections received by said cellular device, said pseudorangecorrections selected from a group consisting of Differential GlobalPositioning System (DGPS), Precise Point Positioning (PPP), Real TimeKinematic (RTK), and RTX.
 29. The non-transitory computer readablestorage medium of claim 25 wherein said method further comprises:accessing Wide Area Augmentation System (WAAS) pseudorange correctionsusing accessing logic of said cellular device; storing the WAASpseudorange corrections in a memory device of said cellular device;accessing the smoothed pseudorange information and the WAAS pseudorangecorrections using pseudorange information processing logic of saidcellular device; and determining a position fix of said circularlypolarized GNSS antenna using the pseudorange information processinglogic based on the smoothed pseudorange information and the WAASpseudorange corrections using said processor.
 30. The non-transitorycomputer readable storage medium of claim 24 wherein said method furthercomprises: determining whether to apply any improvements to thepseudorange information using position accuracy improvementdetermination logic of said cellular device; and determining one or moreimprovements to be applied to the pseudorange information, if thedetermination is that any improvements will be applied using theposition accuracy improvement determination logic of said cellulardevice.
 31. The non-transitory computer readable storage medium of claim20 wherein said method further comprises: disposing said GNSS chipset,said circularly polarized GNSS antenna, and a wireless communicationcomponent in a housing of a receiving component which is separate fromsaid cellular device.
 32. The non-transitory computer readable storagemedium of claim 31 wherein said method further comprises: coupling saidreceiving component with an article of clothing.
 33. The non-transitorycomputer readable storage medium of claim 32 wherein said article ofclothing comprises a solar panel configured to generate electricity, andwherein said method further comprises: using said solar panel torecharge a battery disposed within said receiving component.
 34. Thenon-transitory computer readable storage medium of claim 31 wherein saidmethod further comprises: disposing said receiving component with asupport pole used to locate a point on the ground.
 35. Thenon-transitory computer readable storage medium of claim 31 wherein saidmethod further comprises: disposing said receiving component upon amoveable traffic management device.
 36. The non-transitory computerreadable storage medium of claim 20 wherein said method furthercomprises: using an abbreviated feature set GNSS chipset as said GNSSchipset.
 37. The non-transitory computer readable storage medium ofclaim 20 wherein said method further comprises: using a GNSS chipsetconfigured to process at least one of an L1 GNSS signal and an L2C GNSSsignal as said chipset.
 38. The non-transitory computer readable storagemedium of claim 20 wherein the GNSS corrections from said at least onecorrection source are not contained in a GNSS signal.
 39. A GlobalNavigation Satellite System (GNSS) positioning system comprising: areceiving component comprising: a circularly polarized GNSS antennaconfigured to receive a plurality of GNSS satellite signals; a GNSSchipset configured to derive GNSS raw observables information from saidplurality of GNSS satellite signals; and a first wireless communicationcomponent for wirelessly conveying the GNSS raw observables information;and a cellular device which is physically remote from said circularlypolarized GNSS antenna and said GNSS chipset, comprising: a secondwireless communication component configured to receive the GNSS rawobservables information from said receiving component; and a processorconfigured to access the GNSS raw observables information and to derivea position of said GNSS antenna based upon GNSS raw observablesinformation in combination with GNSS corrections received from at leastone correction source.
 40. The GNSS positioning system of claim 39wherein said processor comprises a primary processor of said cellulardevice.
 41. The GNSS positioning system of claim 39 wherein said rawGNSS observables information comprises carrier phase information. 42.The GNSS positioning system of claim 39 wherein said raw GNSSobservables information comprises Doppler shift information.
 43. TheGNSS positioning system of claim 39 wherein said raw GNSS observablesinformation comprises pseudorange information.
 44. The GNSS positioningsystem of claim 43 wherein said cellular device further comprises:smoothing logic for smoothing said pseudorange information to createsmoothed pseudorange information.
 45. The GNSS positioning system ofclaim 44 wherein said cellular device further comprises: real carrierphase logic for smoothing the pseudorange information based on realcarrier phase information that is derived based on the carrier phaseinformation.
 46. The GNSS positioning system of claim 44 wherein saidcellular device further comprises: correcting logic for correcting thesmoothed pseudorange information to create corrected pseudoranges. 47.The GNSS positioning system of claim 46, wherein the correctedpseudoranges are pseudoranges that were corrected based on one or moretypes of pseudorange corrections received via a third wirelesscommunication component of said cellular device, said pseudorangecorrections selected from a group consisting of Differential GlobalPositioning System (DGPS), Precise Point Positioning (PPP), Real TimeKinematic (RTK), and RTX.
 48. The GNSS positioning system of claim 44wherein said cellular device further comprises: accessing logicconfigured to access Wide Area Augmentation System (WAAS) pseudorangecorrections; a memory configured to store the WAAS pseudorangecorrections; and pseudorange information processing logic configured toaccess the smoothed pseudorange information and the WAAS pseudorangecorrections and wherein said processor is configured to determine aposition fix of said circularly polarized GNSS antenna using thepseudorange information processing logic based on the smoothedpseudorange information and the WAAS pseudorange corrections.
 49. TheGNSS positioning system of claim 39, wherein said cellular devicefurther comprises: position accuracy improvement determination logic fordetermining whether to apply any improvements to pseudorange informationand for determining one or more improvements to be applied topseudorange information, if the determination is that any improvementswill be applied.
 50. The GNSS positioning system of claim 39 furthercomprising: disposing said GNSS chipset, said circularly polarized GNSSantenna, and a wireless communication component in a housing of areceiving component which is separate from said cellular device.
 51. TheGNSS positioning system of claim 50 wherein said receiving component iscoupled with an article of clothing.
 52. The GNSS positioning system ofclaim 51 wherein said article of clothing further comprises a solarpanel configured to generate electricity and is used to recharge abattery disposed within said receiving component.
 53. The GNSSpositioning system of claim 50 wherein said receiving component iscoupled with a support pole used to locate a point on the ground. 54.The GNSS positioning system of claim 50 said receiving component isdisposed upon a moveable traffic management device.
 55. The GNSSpositioning system of claim 39 wherein said GNSS chipset comprises anabbreviated feature set GNSS chipset.
 56. The GNSS positioning system ofclaim 39 wherein said GNSS chipset is configured to process at least oneof an L1 GNSS signal and an L2C GNSS signal.
 57. The GNSS positioningsystem of claim 39 wherein the GNSS corrections from said at least onecorrection source are not contained in a GNSS signal.
 58. Ahelmet-mounted Global Navigation Satellite System (GNSS) receiverpositioning system comprising: a hard hat comprising a receivingcomponent, said receiving component comprising: a circularly polarizedGNSS antenna configured to receive respective signals from a pluralityof GNSS satellites; a GNSS chipset configured to provide GNSS rawobservables information from said respective signals of said pluralityof GNSS satellites; and a first wireless communication componentconfigured to transmit the GNSS raw observables information, and whereinsaid circularly polarized GNSS antenna, said GNSS chipset, and saidfirst wireless communication component are disposed within a housing;and a cellular device, which is physically remote from said circularlypolarized GNSS antenna and said GNSS chipset, comprising: a secondwireless communication component configured to receive the GNSS rawobservables information sent by said first wireless communicationcomponent; and a processor configured to process the GNSS rawobservables information in combination with at least one GNSS correctionreceived from at least one correction source to derive a position ofsaid circularly polarized GNSS antenna.
 59. The helmet-mounted GNSSreceiver positioning system of claim 58 wherein said circularlypolarized GNSS antenna comprises a GNSS patch antenna.
 60. Thehelmet-mounted GNSS receiver positioning system of claim 58 wherein saidGNSS chipset comprises an abbreviated feature set GNSS chipset.
 61. Thehelmet-mounted GNSS receiver positioning system of claim 58 wherein saidGNSS chipset is configured to process at least one of an L1 GNSS signaland an L2C GNSS signal.
 62. The helmet-mounted GNSS receiver positioningsystem of claim 58 further comprising: a rechargeable battery disposedwithin said housing.
 63. The helmet-mounted GNSS receiver positioningsystem of claim 62 further comprising: a power connection disposedwithin said housing configured to receive electrical power from a solarpanel disposed upon said hard hat; and a power line conditioner disposedwithin said housing and coupled with said power connection and saidrechargeable battery, said power line conditioner configured to convertpower received via said power connection to a voltage suitable forre-charging said rechargeable battery.
 64. The helmet-mounted GNSSreceiver positioning system of claim 63 wherein said hard hat furthercomprises: a compartment disposed at the top of said hard hat andconfigured to contain said receiving component; an electrical connectionfor providing electrical power to said receiving component from saidsolar panel; and a cover for said compartment configured to protect saidreceiving component from moisture, dust, and impact.
 65. Thehelmet-mounted GNSS receiver positioning system of claim 63 wherein saidhard hat further comprises: a compartment disposed on the underside ofsaid hard hat and configured to contain said receiving component; anelectrical connection for providing electrical power to said receivingcomponent from said solar panel; and a cover for said compartmentconfigured to protect said receiving component from moisture, dust, andimpact.
 66. The helmet-mounted GNSS receiver positioning system of claim58 wherein said wireless communication component is configured tooperate in compliance with the IEEE 802.15.4 specification for personalarea networks.
 67. The helmet-mounted GNSS receiver positioning systemof claim 58 wherein said wireless communication component is configuredto operate in compliance with the Instrument Scientific and Medical(ISM) band of the radio frequency spectrum in the 2400-2484 MHz range.68. The helmet-mounted GNSS receiver positioning system of claim 58wherein said raw GNSS observables information comprises pseudorangeinformation.
 69. The helmet-mounted GNSS receiver positioning system ofclaim 58 wherein said raw GNSS observables information comprises carrierphase information.
 70. The helmet-mounted GNSS receiver positioningsystem of claim 58 wherein said raw GNSS observables informationcomprises Doppler shift information.